From 98097a5d322e00ecee9170b234320f6bcd946c8a Mon Sep 17 00:00:00 2001
From: Ben Jones <ben@pseudonym.party>
Date: Sun, 14 Mar 2021 21:49:51 -0700
Subject: [PATCH 1/7] fix last compiler warns, add value transfer

---
 .../OVM/accounts/OVM_ECDSAContractAccount.sol | 58 +++++++++++++++----
 1 file changed, 47 insertions(+), 11 deletions(-)

diff --git a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
index ee013f1e6934..2dbee61def19 100644
--- a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
@@ -101,13 +101,10 @@ contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
         // Transfer fee to relayer.
         address relayer = Lib_SafeExecutionManagerWrapper.safeCALLER();
         uint256 fee = Lib_SafeMathWrapper.mul(decodedTx.gasLimit, decodedTx.gasPrice);
-        (bool success, ) = Lib_SafeExecutionManagerWrapper.safeCALL(
-            gasleft(),
-            ETH_ERC20_ADDRESS,
-            abi.encodeWithSignature("transfer(address,uint256)", relayer, fee)
-        );
         Lib_SafeExecutionManagerWrapper.safeREQUIRE(
-            success == true,
+            _attemptETHTransfer(
+                relayer, fee
+            ),
             "Fee was not transferred to relayer."
         );
 
@@ -130,11 +127,50 @@ contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
             // cases, but since this is a contract we'd end up bumping the nonce twice.
             Lib_SafeExecutionManagerWrapper.safeINCREMENTNONCE();
 
-            return Lib_SafeExecutionManagerWrapper.safeCALL(
-                gasleft(),
-                decodedTx.to,
-                decodedTx.data
-            );
+            if (transaction.value > 0) {
+                Lib_SafeExecutionManagerWrapper.safeREQUIRE(
+                    transaction.data.length == 0,
+                    "Sending ETH with data is currently unsupported."
+                );
+
+                return (
+                    _attemptETHTransfer(transaction.to, transaction.value),
+                    bytes('')
+                );
+            } else {
+                return Lib_SafeExecutionManagerWrapper.safeCALL(
+                    gasleft(),
+                    decodedTx.to,
+                    decodedTx.data
+                );
+            }
         }
     }
+
+    /**
+     * Attempts to tansfer OVM_ETH.
+     * @param _to Address to send the L2 ETH to.
+     * @param _value Amount of L2 ETH to send.
+     * @return Whether the transfer was successful.
+     */
+    function _attemptETHTransfer(
+        address _to,
+        uint256 _value
+    )
+        internal
+        returns(
+            bool
+        )
+    {
+        (bool success, ) = Lib_SafeExecutionManagerWrapper.safeCALL(
+            gasleft(),
+            ETH_ERC20_ADDRESS,
+            abi.encodeWithSignature(
+                "transfer(address,uint256)",
+                _to,
+                _value
+            )
+        );
+        return success;
+    }
 }

From 220b80e3a51180e10dc7577384f0087abf85556b Mon Sep 17 00:00:00 2001
From: Ben Jones <ben@pseudonym.party>
Date: Sun, 14 Mar 2021 22:49:56 -0700
Subject: [PATCH 2/7] lower nonce size

---
 .../OVM/accounts/OVM_ECDSAContractAccount.sol |  6 ++---
 .../OVM/execution/OVM_ExecutionManager.sol    | 18 +++++++--------
 .../OVM/execution/OVM_StateManager.sol        |  4 ++--
 .../iOVM/execution/iOVM_ExecutionManager.sol  |  2 +-
 .../iOVM/execution/iOVM_StateManager.sol      |  4 ++--
 .../libraries/codec/Lib_OVMCodec.sol          |  8 +++----
 .../libraries/rlp/Lib_RLPReader.sol           | 22 +++++++++++++++++++
 .../Lib_SafeExecutionManagerWrapper.sol       | 10 ++++-----
 .../OVM_ExecutionManager/ovmCREATE.spec.ts    | 18 +++++++++++++++
 9 files changed, 66 insertions(+), 26 deletions(-)

diff --git a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
index 2dbee61def19..1e13cc04b23b 100644
--- a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
@@ -127,14 +127,14 @@ contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
             // cases, but since this is a contract we'd end up bumping the nonce twice.
             Lib_SafeExecutionManagerWrapper.safeINCREMENTNONCE();
 
-            if (transaction.value > 0) {
+            if (decodedTx.value > 0) {
                 Lib_SafeExecutionManagerWrapper.safeREQUIRE(
-                    transaction.data.length == 0,
+                    decodedTx.data.length == 0,
                     "Sending ETH with data is currently unsupported."
                 );
 
                 return (
-                    _attemptETHTransfer(transaction.to, transaction.value),
+                    _attemptETHTransfer(decodedTx.to, decodedTx.value),
                     bytes('')
                 );
             } else {
diff --git a/packages/contracts/contracts/optimistic-ethereum/OVM/execution/OVM_ExecutionManager.sol b/packages/contracts/contracts/optimistic-ethereum/OVM/execution/OVM_ExecutionManager.sol
index dba6fa1db2ff..b05273245471 100644
--- a/packages/contracts/contracts/optimistic-ethereum/OVM/execution/OVM_ExecutionManager.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/OVM/execution/OVM_ExecutionManager.sol
@@ -460,7 +460,7 @@ contract OVM_ExecutionManager is iOVM_ExecutionManager, Lib_AddressResolver {
         override
         public
         returns (
-            uint256 _nonce
+            uint64 _nonce
         )
     {
         return _getAccountNonce(ovmADDRESS());
@@ -475,7 +475,7 @@ contract OVM_ExecutionManager is iOVM_ExecutionManager, Lib_AddressResolver {
         notStatic
     {
         address account = ovmADDRESS();
-        uint256 nonce = _getAccountNonce(account);
+        uint64 nonce = _getAccountNonce(account);
 
         // Prevent overflow.
         if (nonce + 1 > nonce) {
@@ -1050,15 +1050,15 @@ contract OVM_ExecutionManager is iOVM_ExecutionManager, Lib_AddressResolver {
      * This function sanitizes the return types for creation messages to match calls (bool, bytes),
      * by being an external function which the EM can call, that mimics the success/fail case of the CREATE.
      * This allows for consistent handling of both types of messages in _handleExternalMessage().
-     * Having this step occur as a separate call frame also allows us to easily revert the 
+     * Having this step occur as a separate call frame also allows us to easily revert the
      * contract deployment in the event that the code is unsafe.
-     * 
-     * @param _gasLimit Amount of gas to be passed into this creation.
+     *
+     * param _gasLimit Amount of gas to be passed into this creation.
      * @param _creationCode Code to pass into CREATE for deployment.
      * @param _address OVM address being deployed to.
      */
     function safeCREATE(
-        uint _gasLimit,
+        uint, // _gasLimit
         bytes memory _creationCode,
         address _address
     )
@@ -1097,7 +1097,7 @@ contract OVM_ExecutionManager is iOVM_ExecutionManager, Lib_AddressResolver {
         if (ethAddress == address(0)) {
             // If the creation fails, the EVM lets us grab its revert data. This may contain a revert flag
             // to be used above in _handleExternalMessage, so we pass the revert data back up unmodified.
-            assembly { 
+            assembly {
                 returndatacopy(0,0,returndatasize())
                 revert(0, returndatasize())
             }
@@ -1167,7 +1167,7 @@ contract OVM_ExecutionManager is iOVM_ExecutionManager, Lib_AddressResolver {
      */
     function _setAccountNonce(
         address _address,
-        uint256 _nonce
+        uint64 _nonce
     )
         internal
     {
@@ -1185,7 +1185,7 @@ contract OVM_ExecutionManager is iOVM_ExecutionManager, Lib_AddressResolver {
     )
         internal
         returns (
-            uint256 _nonce
+            uint64 _nonce
         )
     {
         _checkAccountLoad(_address);
diff --git a/packages/contracts/contracts/optimistic-ethereum/OVM/execution/OVM_StateManager.sol b/packages/contracts/contracts/optimistic-ethereum/OVM/execution/OVM_StateManager.sol
index 2d8a95bc13e6..0f08a30d976b 100644
--- a/packages/contracts/contracts/optimistic-ethereum/OVM/execution/OVM_StateManager.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/OVM/execution/OVM_StateManager.sol
@@ -207,7 +207,7 @@ contract OVM_StateManager is iOVM_StateManager {
      */
     function setAccountNonce(
         address _address,
-        uint256 _nonce
+        uint64 _nonce
     )
         override
         public
@@ -228,7 +228,7 @@ contract OVM_StateManager is iOVM_StateManager {
         public
         view
         returns (
-            uint256
+            uint64
         )
     {
         return accounts[_address].nonce;
diff --git a/packages/contracts/contracts/optimistic-ethereum/iOVM/execution/iOVM_ExecutionManager.sol b/packages/contracts/contracts/optimistic-ethereum/iOVM/execution/iOVM_ExecutionManager.sol
index 9be045cfc748..3f4cfe889004 100644
--- a/packages/contracts/contracts/optimistic-ethereum/iOVM/execution/iOVM_ExecutionManager.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/iOVM/execution/iOVM_ExecutionManager.sol
@@ -117,7 +117,7 @@ interface iOVM_ExecutionManager {
      * Account Abstraction Opcodes *
      ******************************/
 
-    function ovmGETNONCE() external returns (uint256 _nonce);
+    function ovmGETNONCE() external returns (uint64 _nonce);
     function ovmINCREMENTNONCE() external;
     function ovmCREATEEOA(bytes32 _messageHash, uint8 _v, bytes32 _r, bytes32 _s) external;
 
diff --git a/packages/contracts/contracts/optimistic-ethereum/iOVM/execution/iOVM_StateManager.sol b/packages/contracts/contracts/optimistic-ethereum/iOVM/execution/iOVM_StateManager.sol
index 1c4870a5841a..9497752ad9ba 100644
--- a/packages/contracts/contracts/optimistic-ethereum/iOVM/execution/iOVM_StateManager.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/iOVM/execution/iOVM_StateManager.sol
@@ -45,8 +45,8 @@ interface iOVM_StateManager {
     function getAccount(address _address) external view returns (Lib_OVMCodec.Account memory _account);
     function hasAccount(address _address) external view returns (bool _exists);
     function hasEmptyAccount(address _address) external view returns (bool _exists);
-    function setAccountNonce(address _address, uint256 _nonce) external;
-    function getAccountNonce(address _address) external view returns (uint256 _nonce);
+    function setAccountNonce(address _address, uint64 _nonce) external;
+    function getAccountNonce(address _address) external view returns (uint64 _nonce);
     function getAccountEthAddress(address _address) external view returns (address _ethAddress);
     function getAccountStorageRoot(address _address) external view returns (bytes32 _storageRoot);
     function initPendingAccount(address _address) external;
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol
index 0cb7245956a5..4c3c94a7424b 100644
--- a/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol
@@ -34,7 +34,7 @@ library Lib_OVMCodec {
      ***********/
 
     struct Account {
-        uint256 nonce;
+        uint64 nonce;
         uint256 balance;
         bytes32 storageRoot;
         bytes32 codeHash;
@@ -43,7 +43,7 @@ library Lib_OVMCodec {
     }
 
     struct EVMAccount {
-        uint256 nonce;
+        uint64 nonce;
         uint256 balance;
         bytes32 storageRoot;
         bytes32 codeHash;
@@ -307,7 +307,7 @@ library Lib_OVMCodec {
         // index-by-index circumvents this issue.
         raw[0] = Lib_RLPWriter.writeBytes(
             Lib_Bytes32Utils.removeLeadingZeros(
-                bytes32(_account.nonce)
+                bytes32(uint256(_account.nonce))
             )
         );
         raw[1] = Lib_RLPWriter.writeBytes(
@@ -338,7 +338,7 @@ library Lib_OVMCodec {
         Lib_RLPReader.RLPItem[] memory accountState = Lib_RLPReader.readList(_encoded);
 
         return EVMAccount({
-            nonce: Lib_RLPReader.readUint256(accountState[0]),
+            nonce: uint64(Lib_RLPReader.readUint256(accountState[0])),
             balance: Lib_RLPReader.readUint256(accountState[1]),
             storageRoot: Lib_RLPReader.readBytes32(accountState[2]),
             codeHash: Lib_RLPReader.readBytes32(accountState[3])
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPReader.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPReader.sol
index 5e81c5de2ae6..b0b198996a8a 100644
--- a/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPReader.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPReader.sol
@@ -425,6 +425,28 @@ library Lib_RLPReader {
         );
     }
 
+    /**
+     * Reads an RLP Uint64 value into a uint64.
+     * @param _in RLP uint64 value.
+     * @return Decoded uint64.
+     */
+    function readUint64(
+        RLPItem memory _in
+    )
+        internal
+        pure
+        returns (
+            uint64
+        )
+    {
+        require(
+            _in.length <= 9,
+            "Invalid RLP uint64 value."
+        );
+
+        return uint64(readUint256(_in));
+    }
+
     /**
      * Reads the raw bytes of an RLP item.
      * @param _in RLP item to read.
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol
index 14dc89bdf8ed..b0885d6a879f 100644
--- a/packages/contracts/contracts/optimistic-ethereum/libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol
@@ -6,10 +6,10 @@ import { Lib_ErrorUtils } from "../utils/Lib_ErrorUtils.sol";
 
 /**
  * @title Lib_SafeExecutionManagerWrapper
- * @dev The Safe Execution Manager Wrapper provides functions which facilitate writing OVM safe 
- * code using the standard solidity compiler, by routing all its operations through the Execution 
+ * @dev The Safe Execution Manager Wrapper provides functions which facilitate writing OVM safe
+ * code using the standard solidity compiler, by routing all its operations through the Execution
  * Manager.
- * 
+ *
  * Compiler used: solc
  * Runtime target: OVM
  */
@@ -195,7 +195,7 @@ library Lib_SafeExecutionManagerWrapper {
     function safeGETNONCE()
         internal
         returns (
-            uint256 _nonce
+            uint64 _nonce
         )
     {
         bytes memory returndata = _safeExecutionManagerInteraction(
@@ -204,7 +204,7 @@ library Lib_SafeExecutionManagerWrapper {
             )
         );
 
-        return abi.decode(returndata, (uint256));
+        return abi.decode(returndata, (uint64));
     }
 
     /**
diff --git a/packages/contracts/test/contracts/OVM/execution/OVM_ExecutionManager/ovmCREATE.spec.ts b/packages/contracts/test/contracts/OVM/execution/OVM_ExecutionManager/ovmCREATE.spec.ts
index 147fac7be9f0..c4caf60103cd 100644
--- a/packages/contracts/test/contracts/OVM/execution/OVM_ExecutionManager/ovmCREATE.spec.ts
+++ b/packages/contracts/test/contracts/OVM/execution/OVM_ExecutionManager/ovmCREATE.spec.ts
@@ -744,6 +744,24 @@ const test_ovmCREATE: TestDefinition = {
         },
       ],
     },
+    {
+      name: 'ovmCREATE(UNSAFE_CODE)',
+      steps: [
+        {
+          functionName: 'ovmCREATE',
+          functionParams: {
+            bytecode: UNSAFE_BYTECODE,
+          },
+          expectedReturnStatus: true,
+          expectedReturnValue: {
+            address: constants.AddressZero,
+            revertData: encodeSolidityError(
+              'Constructor attempted to deploy unsafe bytecode.'
+            ),
+          },
+        },
+      ],
+    },
   ],
   subTests: [
     {

From af9f9a65a452755f64cd33999426c8238ed081c7 Mon Sep 17 00:00:00 2001
From: Kelvin Fichter <kelvinfichter@gmail.com>
Date: Mon, 8 Mar 2021 15:06:36 -0800
Subject: [PATCH 3/7] Merge branch 'master' into feat/standard-rlp-transaction

---
 .../OVM/accounts/OVM_ECDSAContractAccount.sol |  52 +-
 .../OVM/accounts/OVM_ProxyEOA.sol             |   2 -
 .../predeploys/OVM_SequencerEntrypoint.sol    | 118 +--
 .../accounts/iOVM_ECDSAContractAccount.sol    |  16 +-
 .../libraries/codec/Lib_EIP155Tx.sol          | 196 +++++
 .../libraries/codec/Lib_OVMCodec.sol          | 137 ----
 .../libraries/rlp/Lib_RLPWriter.sol           |  17 +
 .../libraries/utils/Lib_ECDSAUtils.sol        |  98 ---
 .../accounts/mockOVM_ECDSAContractAccount.sol |  95 ---
 .../test-libraries/codec/TestLib_EIP155Tx.sol |  71 ++
 .../test-libraries/codec/TestLib_OVMCodec.sol |  24 -
 .../utils/TestLib_ECDSAUtils.sol              |  33 -
 .../src/contract-deployment/config.ts         |   3 -
 .../accounts/OVM_ECDSAContractAccount.spec.ts | 140 +---
 .../OVM_SequencerEntrypoint.spec.ts           | 128 +---
 .../contracts/libraries/codec/Lib_EIP155Tx.ts |  15 +
 .../libraries/utils/Lib_ECDSAUtils.spec.ts    |   9 -
 packages/contracts/test/data/index.ts         |   2 +-
 .../libraries/codec/Lib_EIP155Tx.test.json    | 725 ++++++++++++++++++
 .../libraries/codec/Lib_OVMCodec.test.json    |  18 -
 .../libraries/utils/Lib_ECDSAUtils.test.json  | 126 ---
 .../contracts/test/helpers/codec/encoding.ts  | 116 ---
 .../helpers/test-runner/json-test-runner.ts   |  10 +-
 23 files changed, 1148 insertions(+), 1003 deletions(-)
 create mode 100644 packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_EIP155Tx.sol
 delete mode 100644 packages/contracts/contracts/optimistic-ethereum/libraries/utils/Lib_ECDSAUtils.sol
 delete mode 100644 packages/contracts/contracts/optimistic-ethereum/mockOVM/accounts/mockOVM_ECDSAContractAccount.sol
 create mode 100644 packages/contracts/contracts/test-libraries/codec/TestLib_EIP155Tx.sol
 delete mode 100644 packages/contracts/contracts/test-libraries/utils/TestLib_ECDSAUtils.sol
 create mode 100644 packages/contracts/test/contracts/libraries/codec/Lib_EIP155Tx.ts
 delete mode 100644 packages/contracts/test/contracts/libraries/utils/Lib_ECDSAUtils.spec.ts
 create mode 100644 packages/contracts/test/data/json/libraries/codec/Lib_EIP155Tx.test.json
 delete mode 100644 packages/contracts/test/data/json/libraries/utils/Lib_ECDSAUtils.test.json

diff --git a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
index 1e13cc04b23b..10c0aa57e76f 100644
--- a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
@@ -6,21 +6,22 @@ pragma experimental ABIEncoderV2;
 import { iOVM_ECDSAContractAccount } from "../../iOVM/accounts/iOVM_ECDSAContractAccount.sol";
 
 /* Library Imports */
-import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
-import { Lib_ECDSAUtils } from "../../libraries/utils/Lib_ECDSAUtils.sol";
+import { Lib_EIP155Tx } from "../../libraries/codec/Lib_EIP155Tx.sol";
 import { Lib_SafeExecutionManagerWrapper } from "../../libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol";
 import { Lib_SafeMathWrapper } from "../../libraries/wrappers/Lib_SafeMathWrapper.sol";
 
 /**
  * @title OVM_ECDSAContractAccount
  * @dev The ECDSA Contract Account can be used as the implementation for a ProxyEOA deployed by the
- * ovmCREATEEOA operation. It enables backwards compatibility with Ethereum's Layer 1, by 
+ * ovmCREATEEOA operation. It enables backwards compatibility with Ethereum's Layer 1, by
  * providing eth_sign and EIP155 formatted transaction encodings.
  *
  * Compiler used: solc
  * Runtime target: OVM
  */
 contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
+    using Lib_EIP155Tx for Lib_EIP155Tx.EIP155Tx;
+
 
     /*************
      * Constants *
@@ -38,20 +39,12 @@ contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
 
     /**
      * Executes a signed transaction.
-     * @param _transaction Signed EOA transaction.
-     * @param _signatureType Hashing scheme used for the transaction (e.g., ETH signed message).
-     * @param _v Signature `v` parameter.
-     * @param _r Signature `r` parameter.
-     * @param _s Signature `s` parameter.
+     * @param _encodedTransaction Signed EIP155 transaction.
      * @return Whether or not the call returned (rather than reverted).
      * @return Data returned by the call.
      */
     function execute(
-        bytes memory _transaction,
-        Lib_OVMCodec.EOASignatureType _signatureType,
-        uint8 _v,
-        bytes32 _r,
-        bytes32 _s
+        bytes memory _encodedTransaction
     )
         override
         public
@@ -60,31 +53,29 @@ contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
             bytes memory
         )
     {
-        bool isEthSign = _signatureType == Lib_OVMCodec.EOASignatureType.ETH_SIGNED_MESSAGE;
+        Lib_EIP155Tx.EIP155Tx memory decodedTx = Lib_EIP155Tx.decode(
+            _encodedTransaction,
+            Lib_SafeExecutionManagerWrapper.safeCHAINID()
+        );
+
+        // Recovery parameter being something other than 0 or 1 indicates that this transaction was
+        // signed using the wrong chain ID. We really should have this logic inside of Lib_EIP155Tx
+        // but I'd prefer not to add the "safeREQUIRE" logic into that library. So it'll live here
+        // for now.
+        Lib_SafeExecutionManagerWrapper.safeREQUIRE(
+            decodedTx.recoveryParam < 2,
+            "OVM_ECDSAContractAccount: Transaction was signed with the wrong chain ID."
+        );
 
         // Address of this contract within the ovm (ovmADDRESS) should be the same as the
         // recovered address of the user who signed this message. This is how we manage to shim
         // account abstraction even though the user isn't a contract.
         // Need to make sure that the transaction nonce is right and bump it if so.
         Lib_SafeExecutionManagerWrapper.safeREQUIRE(
-            Lib_ECDSAUtils.recover(
-                _transaction,
-                isEthSign,
-                _v,
-                _r,
-                _s
-            ) == Lib_SafeExecutionManagerWrapper.safeADDRESS(),
+            decodedTx.sender() == Lib_SafeExecutionManagerWrapper.safeADDRESS(),
             "Signature provided for EOA transaction execution is invalid."
         );
 
-        Lib_OVMCodec.EIP155Transaction memory decodedTx = Lib_OVMCodec.decodeEIP155Transaction(_transaction, isEthSign);
-
-        // Need to make sure that the transaction chainId is correct.
-        Lib_SafeExecutionManagerWrapper.safeREQUIRE(
-            decodedTx.chainId == Lib_SafeExecutionManagerWrapper.safeCHAINID(),
-            "Transaction chainId does not match expected OVM chainId."
-        );
-
         // Need to make sure that the transaction nonce is right.
         Lib_SafeExecutionManagerWrapper.safeREQUIRE(
             decodedTx.nonce == Lib_SafeExecutionManagerWrapper.safeGETNONCE(),
@@ -98,7 +89,8 @@ contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
         //    "Gas is not sufficient to execute the transaction."
         // );
 
-        // Transfer fee to relayer.
+        // Transfer fee to relayer. We assume that whoever called this function is the relayer,
+        // hence the usage of CALLER. Fee is computed as gasLimit * gasPrice.
         address relayer = Lib_SafeExecutionManagerWrapper.safeCALLER();
         uint256 fee = Lib_SafeMathWrapper.mul(decodedTx.gasLimit, decodedTx.gasPrice);
         Lib_SafeExecutionManagerWrapper.safeREQUIRE(
diff --git a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ProxyEOA.sol b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ProxyEOA.sol
index 0f376f821fee..16127eb28ea1 100644
--- a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ProxyEOA.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ProxyEOA.sol
@@ -3,8 +3,6 @@ pragma solidity >0.5.0 <0.8.0;
 
 /* Library Imports */
 import { Lib_Bytes32Utils } from "../../libraries/utils/Lib_Bytes32Utils.sol";
-import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
-import { Lib_ECDSAUtils } from "../../libraries/utils/Lib_ECDSAUtils.sol";
 import { Lib_SafeExecutionManagerWrapper } from "../../libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol";
 
 /**
diff --git a/packages/contracts/contracts/optimistic-ethereum/OVM/predeploys/OVM_SequencerEntrypoint.sol b/packages/contracts/contracts/optimistic-ethereum/OVM/predeploys/OVM_SequencerEntrypoint.sol
index bba7dd59c90f..0d4194c49290 100644
--- a/packages/contracts/contracts/optimistic-ethereum/OVM/predeploys/OVM_SequencerEntrypoint.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/OVM/predeploys/OVM_SequencerEntrypoint.sol
@@ -2,9 +2,7 @@
 pragma solidity >0.5.0 <0.8.0;
 
 /* Library Imports */
-import { Lib_BytesUtils } from "../../libraries/utils/Lib_BytesUtils.sol";
-import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
-import { Lib_ECDSAUtils } from "../../libraries/utils/Lib_ECDSAUtils.sol";
+import { Lib_EIP155Tx } from "../../libraries/codec/Lib_EIP155Tx.sol";
 import { Lib_SafeExecutionManagerWrapper } from "../../libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol";
 
 /**
@@ -19,15 +17,7 @@ import { Lib_SafeExecutionManagerWrapper } from "../../libraries/wrappers/Lib_Sa
  * Runtime target: OVM
  */
 contract OVM_SequencerEntrypoint {
-
-    /*********
-     * Enums *
-     *********/
-    
-    enum TransactionType {
-        NATIVE_ETH_TRANSACTION,
-        ETH_SIGNED_MESSAGE
-    }
+    using Lib_EIP155Tx for Lib_EIP155Tx.EIP155Tx;
 
 
     /*********************
@@ -35,93 +25,47 @@ contract OVM_SequencerEntrypoint {
      *********************/
 
     /**
-     * Uses a custom "compressed" format to save on calldata gas:
-     * calldata[00:01]: transaction type (0 == EIP 155, 2 == Eth Sign Message)
-     * calldata[01:33]: signature "r" parameter
-     * calldata[33:65]: signature "s" parameter
-     * calldata[65:66]: signature "v" parameter
-     * calldata[66:69]: transaction gas limit
-     * calldata[69:72]: transaction gas price
-     * calldata[72:75]: transaction nonce
-     * calldata[75:95]: transaction target address
-     * calldata[95:XX]: transaction data
+     * Expects an RLP-encoded EIP155 transaction as input. See the EIP for a more detailed
+     * description of this transaction format:
+     * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-155.md
      */
     fallback()
         external
     {
-        TransactionType transactionType = _getTransactionType(Lib_BytesUtils.toUint8(msg.data, 0));
-
-        bytes32 r = Lib_BytesUtils.toBytes32(Lib_BytesUtils.slice(msg.data, 1, 32));
-        bytes32 s = Lib_BytesUtils.toBytes32(Lib_BytesUtils.slice(msg.data, 33, 32));
-        uint8 v = Lib_BytesUtils.toUint8(msg.data, 65);
-
-        // Remainder is the transaction to execute.
-        bytes memory compressedTx = Lib_BytesUtils.slice(msg.data, 66);
-        bool isEthSignedMessage = transactionType == TransactionType.ETH_SIGNED_MESSAGE;
-
-        // Need to decompress and then re-encode the transaction based on the original encoding.
-        bytes memory encodedTx = Lib_OVMCodec.encodeEIP155Transaction(
-            Lib_OVMCodec.decompressEIP155Transaction(compressedTx),
-            isEthSignedMessage
+        Lib_EIP155Tx.EIP155Tx memory transaction = Lib_EIP155Tx.decode(
+            msg.data,
+            Lib_SafeExecutionManagerWrapper.safeCHAINID()
         );
 
-        address target = Lib_ECDSAUtils.recover(
-            encodedTx,
-            isEthSignedMessage,
-            uint8(v),
-            r,
-            s
+        // Recovery parameter being something other than 0 or 1 indicates that this transaction was
+        // signed using the wrong chain ID. We really should have this logic inside of the 
+        Lib_SafeExecutionManagerWrapper.safeREQUIRE(
+            transaction.recoveryParam < 2,
+            "OVM_SequencerEntrypoint: Transaction was signed with the wrong chain ID."
         );
 
-        if (Lib_SafeExecutionManagerWrapper.safeEXTCODESIZE(target) == 0) {
-            // ProxyEOA has not yet been deployed for this EOA.
-            bytes32 messageHash = Lib_ECDSAUtils.getMessageHash(encodedTx, isEthSignedMessage);
-            Lib_SafeExecutionManagerWrapper.safeCREATEEOA(messageHash, uint8(v), r, s);
-        }
+        // Cache this result since we use it twice. Maybe we could move this caching into
+        // Lib_EIP155Tx but I'd rather not make optimizations like that right now.
+        address sender = transaction.sender();
 
-        // ProxyEOA has been deployed for this EOA, continue to CALL.
-        bytes memory callbytes = abi.encodeWithSignature(
-            "execute(bytes,uint8,uint8,bytes32,bytes32)",
-            encodedTx,
-            isEthSignedMessage,
-            uint8(v),
-            r,
-            s
-        );
+        // Create an EOA contract for this account if it doesn't already exist.
+        if (Lib_SafeExecutionManagerWrapper.safeEXTCODESIZE(sender) == 0) {
+            Lib_SafeExecutionManagerWrapper.safeCREATEEOA(
+                transaction.hash(),
+                transaction.recoveryParam,
+                transaction.r,
+                transaction.s
+            );
+        }
 
+        // Now call into the EOA contract (which should definitely exist).
         Lib_SafeExecutionManagerWrapper.safeCALL(
             gasleft(),
-            target,
-            callbytes
+            sender,
+            abi.encodeWithSignature(
+                "execute(bytes)",
+                msg.data
+            )
         );
     }
-    
-
-    /**********************
-     * Internal Functions *
-     **********************/
-
-    /**
-     * Converts a uint256 into a TransactionType enum.
-     * @param _transactionType Transaction type index.
-     * @return _txType Transaction type enum value.
-     */
-    function _getTransactionType(
-        uint8 _transactionType
-    )
-        internal
-        returns (
-            TransactionType _txType
-        )
-    {
-        if (_transactionType == 0) {
-            return TransactionType.NATIVE_ETH_TRANSACTION;
-        } if (_transactionType == 2) {
-            return TransactionType.ETH_SIGNED_MESSAGE;
-        } else {
-            Lib_SafeExecutionManagerWrapper.safeREVERT(
-                "Transaction type must be 0 or 2"
-            );
-        }
-    }
 }
diff --git a/packages/contracts/contracts/optimistic-ethereum/iOVM/accounts/iOVM_ECDSAContractAccount.sol b/packages/contracts/contracts/optimistic-ethereum/iOVM/accounts/iOVM_ECDSAContractAccount.sol
index 16c956580f85..7f3fb0f82b52 100644
--- a/packages/contracts/contracts/optimistic-ethereum/iOVM/accounts/iOVM_ECDSAContractAccount.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/iOVM/accounts/iOVM_ECDSAContractAccount.sol
@@ -2,9 +2,6 @@
 pragma solidity >0.5.0 <0.8.0;
 pragma experimental ABIEncoderV2;
 
-/* Library Imports */
-import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
-
 /**
  * @title iOVM_ECDSAContractAccount
  */
@@ -15,10 +12,11 @@ interface iOVM_ECDSAContractAccount {
      ********************/
 
     function execute(
-        bytes memory _transaction,
-        Lib_OVMCodec.EOASignatureType _signatureType,
-        uint8 _v,
-        bytes32 _r,
-        bytes32 _s
-    ) external returns (bool _success, bytes memory _returndata);
+        bytes memory _encodedTransaction
+    )
+        external
+        returns (
+            bool,
+            bytes memory
+        );
 }
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_EIP155Tx.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_EIP155Tx.sol
new file mode 100644
index 000000000000..8fa76433247b
--- /dev/null
+++ b/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_EIP155Tx.sol
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >0.5.0 <0.8.0;
+pragma experimental ABIEncoderV2;
+
+/* Library Imports */
+import { Lib_RLPReader } from "../rlp/Lib_RLPReader.sol";
+import { Lib_RLPWriter } from "../rlp/Lib_RLPWriter.sol";
+
+/**
+ * @title Lib_EIP155Tx
+ * @dev A simple library for dealing with the transaction type defined by EIP155:
+ *      https://github.com/ethereum/EIPs/blob/master/EIPS/eip-155.md
+ */
+library Lib_EIP155Tx {
+
+    /***********
+     * Structs *
+     ***********/
+
+    // Struct representing an EIP155 transaction. See EIP link above for more information.
+    struct EIP155Tx {
+        // These fields correspond to the actual RLP-encoded fields specified by EIP155.
+        uint256 nonce;
+        uint256 gasPrice;
+        uint256 gasLimit;
+        address to;
+        uint256 value;
+        bytes data;
+        uint8 v;
+        bytes32 r;
+        bytes32 s;
+
+        // Chain ID to associate this transaction with. Used all over the place, seemed easier to
+        // set this once when we create the transaction rather than providing it as an input to
+        // each function. I don't see a strong need to have a transaction with a mutable chain ID.
+        uint256 chainId;
+
+        // The ECDSA "recovery parameter," should always be 0 or 1. EIP155 specifies that:
+        // `v = {0,1} + CHAIN_ID * 2 + 35`
+        // Where `{0,1}` is a stand in for our `recovery_parameter`. Now computing our formula for
+        // the recovery parameter:
+        // 1. `v = {0,1} + CHAIN_ID * 2 + 35`
+        // 2. `v = recovery_parameter + CHAIN_ID * 2 + 35`
+        // 3. `v - CHAIN_ID * 2 - 35 = recovery_parameter`
+        // So we're left with the final formula:
+        // `recovery_parameter = v - CHAIN_ID * 2 - 35`
+        // NOTE: This variable is a uint8 because `v` is inherently limited to a uint8. If we
+        // didn't use a uint8, then recovery_parameter would always be a negative number for chain
+        // IDs greater than 110 (`255 - 110 * 2 - 35 = 0`). So we need to wrap around to support
+        // anything larger.
+        uint8 recoveryParam; 
+
+        // Whether or not the transaction is a creation. Necessary because we can't make an address
+        // "nil". Using the zero address creates a potential conflict if the user did actually
+        // intend to send a transaction to the zero address.
+        bool isCreate;       
+    }
+
+    // Lets us use nicer syntax.
+    using Lib_EIP155Tx for EIP155Tx;
+
+
+    /**********************
+     * Internal Functions *
+     **********************/
+
+    /**
+     * Decodes an EIP155 transaction and attaches a given Chain ID.
+     * Transaction *must* be RLP-encoded.
+     * @param _encoded RLP-encoded EIP155 transaction.
+     * @param _chainId Chain ID to assocaite with this transaction.
+     * @return Parsed transaction.
+     */
+    function decode(
+        bytes memory _encoded,
+        uint256 _chainId
+    )
+        internal
+        pure
+        returns (
+            EIP155Tx memory
+        )
+    {
+        Lib_RLPReader.RLPItem[] memory decoded = Lib_RLPReader.readList(_encoded);
+
+        // Note formula above about how recoveryParam is computed.
+        uint8 v = uint8(Lib_RLPReader.readUint256(decoded[6]));
+        uint8 recoveryParam = uint8(v - 2 * _chainId - 35);
+
+        // Creations can be detected by looking at the byte length here.
+        bool isCreate = Lib_RLPReader.readBytes(decoded[3]).length == 0;
+
+        return EIP155Tx({
+            nonce: Lib_RLPReader.readUint256(decoded[0]),
+            gasPrice: Lib_RLPReader.readUint256(decoded[1]),
+            gasLimit: Lib_RLPReader.readUint256(decoded[2]),
+            to: Lib_RLPReader.readAddress(decoded[3]),
+            value: Lib_RLPReader.readUint256(decoded[4]),
+            data: Lib_RLPReader.readBytes(decoded[5]),
+            v: v,
+            r: Lib_RLPReader.readBytes32(decoded[7]),
+            s: Lib_RLPReader.readBytes32(decoded[8]),
+            chainId: _chainId,
+            recoveryParam: recoveryParam,
+            isCreate: isCreate
+        });
+    }
+
+    /**
+     * Encodes an EIP155 transaction into RLP.
+     * @param _transaction EIP155 transaction to encode.
+     * @param _includeSignature Whether or not to encode the signature.
+     * @return RLP-encoded transaction.
+     */
+    function encode(
+        EIP155Tx memory _transaction,
+        bool _includeSignature
+    )
+        internal
+        pure
+        returns (
+            bytes memory
+        )
+    {
+        bytes[] memory raw = new bytes[](9);
+
+        raw[0] = Lib_RLPWriter.writeUint(_transaction.nonce);
+        raw[1] = Lib_RLPWriter.writeUint(_transaction.gasPrice);
+        raw[2] = Lib_RLPWriter.writeUint(_transaction.gasLimit);
+
+        // We write the encoding of empty bytes when the transaction is a creation, *not* the zero
+        // address as one might assume.
+        if (_transaction.isCreate) {
+            raw[3] = Lib_RLPWriter.writeBytes('');
+        } else {
+            raw[3] = Lib_RLPWriter.writeAddress(_transaction.to);
+        }
+
+        raw[4] = Lib_RLPWriter.writeUint(_transaction.value);
+        raw[5] = Lib_RLPWriter.writeBytes(_transaction.data);
+
+        if (_includeSignature) {
+            raw[6] = Lib_RLPWriter.writeUint(_transaction.v);
+            raw[7] = Lib_RLPWriter.writeBytes32(_transaction.r);
+            raw[8] = Lib_RLPWriter.writeBytes32(_transaction.s);
+        } else {
+            // Chain ID *is* included in the unsigned transaction.
+            raw[6] = Lib_RLPWriter.writeUint(_transaction.chainId); 
+            raw[7] = Lib_RLPWriter.writeBytes('');
+            raw[8] = Lib_RLPWriter.writeBytes('');
+        }
+
+        return Lib_RLPWriter.writeList(raw);
+    }
+
+    /**
+     * Computes the hash of an EIP155 transaction. Assumes that you don't want to include the
+     * signature in this hash because that's a very uncommon usecase. If you really want to include
+     * the signature, just encode with the signature and take the hash yourself.
+     */
+    function hash(
+        EIP155Tx memory _transaction
+    )
+        internal
+        pure
+        returns (
+            bytes32
+        )
+    {
+        return keccak256(
+            _transaction.encode(false)
+        );
+    }
+
+    /**
+     * Computes the sender of an EIP155 transaction.
+     * @param _transaction EIP155 transaction to get a sender for.
+     * @return Address corresponding to the private key that signed this transaction.
+     */
+    function sender(
+        EIP155Tx memory _transaction
+    )
+        internal
+        pure
+        returns (
+            address
+        )
+    {
+        return ecrecover(
+            _transaction.hash(),
+            _transaction.recoveryParam + 27,
+            _transaction.r,
+            _transaction.s
+        );
+    }
+}
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol
index 4c3c94a7424b..341db0b24381 100644
--- a/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol
@@ -18,11 +18,6 @@ library Lib_OVMCodec {
      * Enums *
      *********/
 
-    enum EOASignatureType {
-        EIP155_TRANSACTION,
-        ETH_SIGNED_MESSAGE
-    }
-
     enum QueueOrigin {
         SEQUENCER_QUEUE,
         L1TOL2_QUEUE
@@ -86,142 +81,10 @@ library Lib_OVMCodec {
         uint40 blockNumber;
     }
 
-    struct EIP155Transaction {
-        uint256 nonce;
-        uint256 gasPrice;
-        uint256 gasLimit;
-        address to;
-        uint256 value;
-        bytes data;
-        uint256 chainId;
-    }
-
-
     /**********************
      * Internal Functions *
      **********************/
 
-    /**
-     * Decodes an EOA transaction (i.e., native Ethereum RLP encoding).
-     * @param _transaction Encoded EOA transaction.
-     * @return Transaction decoded into a struct.
-     */
-    function decodeEIP155Transaction(
-        bytes memory _transaction,
-        bool _isEthSignedMessage
-    )
-        internal
-        pure
-        returns (
-            EIP155Transaction memory
-        )
-    {
-        if (_isEthSignedMessage) {
-            (
-                uint256 _nonce,
-                uint256 _gasLimit,
-                uint256 _gasPrice,
-                uint256 _chainId,
-                address _to,
-                bytes memory _data
-            ) = abi.decode(
-                _transaction,
-                (uint256, uint256, uint256, uint256, address ,bytes)
-            );
-            return EIP155Transaction({
-                nonce: _nonce,
-                gasPrice: _gasPrice,
-                gasLimit: _gasLimit,
-                to: _to,
-                value: 0,
-                data: _data,
-                chainId: _chainId
-            });
-        } else {
-            Lib_RLPReader.RLPItem[] memory decoded = Lib_RLPReader.readList(_transaction);
-
-            return EIP155Transaction({
-                nonce: Lib_RLPReader.readUint256(decoded[0]),
-                gasPrice: Lib_RLPReader.readUint256(decoded[1]),
-                gasLimit: Lib_RLPReader.readUint256(decoded[2]),
-                to: Lib_RLPReader.readAddress(decoded[3]),
-                value: Lib_RLPReader.readUint256(decoded[4]),
-                data: Lib_RLPReader.readBytes(decoded[5]),
-                chainId:  Lib_RLPReader.readUint256(decoded[6])
-            });
-        }
-    }
-
-    /**
-     * Decompresses a compressed EIP155 transaction.
-     * @param _transaction Compressed EIP155 transaction bytes.
-     * @return Transaction parsed into a struct.
-     */
-    function decompressEIP155Transaction(
-        bytes memory _transaction
-    )
-        internal
-        returns (
-            EIP155Transaction memory
-        )
-    {
-        return EIP155Transaction({
-            gasLimit: Lib_BytesUtils.toUint24(_transaction, 0),
-            gasPrice: uint256(Lib_BytesUtils.toUint24(_transaction, 3)) * 1000000,
-            nonce: Lib_BytesUtils.toUint24(_transaction, 6),
-            to: Lib_BytesUtils.toAddress(_transaction, 9),
-            data: Lib_BytesUtils.slice(_transaction, 29),
-            chainId: Lib_SafeExecutionManagerWrapper.safeCHAINID(),
-            value: 0
-        });
-    }
-
-    /**
-     * Encodes an EOA transaction back into the original transaction.
-     * @param _transaction EIP155transaction to encode.
-     * @param _isEthSignedMessage Whether or not this was an eth signed message.
-     * @return Encoded transaction.
-     */
-    function encodeEIP155Transaction(
-        EIP155Transaction memory _transaction,
-        bool _isEthSignedMessage
-    )
-        internal
-        pure
-        returns (
-            bytes memory
-        )
-    {
-        if (_isEthSignedMessage) {
-            return abi.encode(
-                _transaction.nonce,
-                _transaction.gasLimit,
-                _transaction.gasPrice,
-                _transaction.chainId,
-                _transaction.to,
-                _transaction.data
-            );
-        } else {
-            bytes[] memory raw = new bytes[](9);
-
-            raw[0] = Lib_RLPWriter.writeUint(_transaction.nonce);
-            raw[1] = Lib_RLPWriter.writeUint(_transaction.gasPrice);
-            raw[2] = Lib_RLPWriter.writeUint(_transaction.gasLimit);
-            if (_transaction.to == address(0)) {
-                raw[3] = Lib_RLPWriter.writeBytes('');
-            } else {
-                raw[3] = Lib_RLPWriter.writeAddress(_transaction.to);
-            }
-            raw[4] = Lib_RLPWriter.writeUint(0);
-            raw[5] = Lib_RLPWriter.writeBytes(_transaction.data);
-            raw[6] = Lib_RLPWriter.writeUint(_transaction.chainId);
-            raw[7] = Lib_RLPWriter.writeBytes(bytes(''));
-            raw[8] = Lib_RLPWriter.writeBytes(bytes(''));
-
-            return Lib_RLPWriter.writeList(raw);
-        }
-    }
-
     /**
      * Encodes a standard OVM transaction.
      * @param _transaction OVM transaction to encode.
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPWriter.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPWriter.sol
index 8040eac0a2fa..4b9c5247bec4 100644
--- a/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPWriter.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPWriter.sol
@@ -92,6 +92,23 @@ library Lib_RLPWriter {
         return writeBytes(abi.encodePacked(_in));
     }
 
+    /**
+     * RLP encodes a bytes32 value.
+     * @param _in The bytes32 to encode.
+     * @return _out The RLP encoded bytes32 in bytes.
+     */
+    function writeBytes32(
+        bytes32 _in
+    )
+        internal
+        pure
+        returns (
+            bytes memory _out
+        )
+    {
+        return writeBytes(abi.encodePacked(_in));
+    }
+
     /**
      * RLP encodes a uint.
      * @param _in The uint256 to encode.
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/utils/Lib_ECDSAUtils.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/utils/Lib_ECDSAUtils.sol
deleted file mode 100644
index 9d973758b920..000000000000
--- a/packages/contracts/contracts/optimistic-ethereum/libraries/utils/Lib_ECDSAUtils.sol
+++ /dev/null
@@ -1,98 +0,0 @@
-// SPDX-License-Identifier: MIT
-pragma solidity >0.5.0 <0.8.0;
-
-/**
- * @title Lib_ECDSAUtils
- */
-library Lib_ECDSAUtils {
-
-    /**************************************
-     * Internal Functions: ECDSA Recovery *
-     **************************************/
-
-    /**
-     * Recovers a signed address given a message and signature.
-     * @param _message Message that was originally signed.
-     * @param _isEthSignedMessage Whether or not the user used the `Ethereum Signed Message` prefix.
-     * @param _v Signature `v` parameter.
-     * @param _r Signature `r` parameter.
-     * @param _s Signature `s` parameter.
-     * @return _sender Signer address.
-     */
-    function recover(
-        bytes memory _message,
-        bool _isEthSignedMessage,
-        uint8 _v,
-        bytes32 _r,
-        bytes32 _s
-    )
-        internal
-        pure
-        returns (
-            address _sender
-        )
-    {
-        bytes32 messageHash = getMessageHash(_message, _isEthSignedMessage);
-
-        return ecrecover(
-            messageHash,
-            _v + 27,
-            _r,
-            _s
-        );
-    }
-
-    function getMessageHash(
-        bytes memory _message,
-        bool _isEthSignedMessage
-    )
-        internal
-        pure
-        returns (bytes32) {
-        if (_isEthSignedMessage) {
-            return getEthSignedMessageHash(_message);
-        }
-        return getNativeMessageHash(_message);
-    }
-
-
-    /*************************************
-     * Private Functions: ECDSA Recovery *
-     *************************************/
-
-    /**
-     * Gets the native message hash (simple keccak256) for a message.
-     * @param _message Message to hash.
-     * @return _messageHash Native message hash.
-     */
-    function getNativeMessageHash(
-        bytes memory _message
-    )
-        private
-        pure
-        returns (
-            bytes32 _messageHash
-        )
-    {
-        return keccak256(_message);
-    }
-
-    /**
-     * Gets the hash of a message with the `Ethereum Signed Message` prefix.
-     * @param _message Message to hash.
-     * @return _messageHash Prefixed message hash.
-     */
-    function getEthSignedMessageHash(
-        bytes memory _message
-    )
-        private
-        pure
-        returns (
-            bytes32 _messageHash
-        )
-    {
-        bytes memory prefix = "\x19Ethereum Signed Message:\n32";
-        bytes32 messageHash = keccak256(_message);
-        return keccak256(abi.encodePacked(prefix, messageHash));
-    }
-}
\ No newline at end of file
diff --git a/packages/contracts/contracts/optimistic-ethereum/mockOVM/accounts/mockOVM_ECDSAContractAccount.sol b/packages/contracts/contracts/optimistic-ethereum/mockOVM/accounts/mockOVM_ECDSAContractAccount.sol
deleted file mode 100644
index 15c51fcf21fb..000000000000
--- a/packages/contracts/contracts/optimistic-ethereum/mockOVM/accounts/mockOVM_ECDSAContractAccount.sol
+++ /dev/null
@@ -1,95 +0,0 @@
-// SPDX-License-Identifier: MIT
-pragma solidity >0.5.0 <0.8.0;
-pragma experimental ABIEncoderV2;
-
-/* Interface Imports */
-import { iOVM_ECDSAContractAccount } from "../../iOVM/accounts/iOVM_ECDSAContractAccount.sol";
-
-/* Library Imports */
-import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
-import { Lib_ECDSAUtils } from "../../libraries/utils/Lib_ECDSAUtils.sol";
-import { Lib_SafeExecutionManagerWrapper } from "../../libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol";
-
-/**
- * @title mockOVM_ECDSAContractAccount
- */
-contract mockOVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
-
-    /********************
-     * Public Functions *
-     ********************/
-
-    /**
-     * Executes a signed transaction.
-     * @param _transaction Signed EOA transaction.
-     * @param _signatureType Hashing scheme used for the transaction (e.g., ETH signed message).
-     * param _v Signature `v` parameter.
-     * param _r Signature `r` parameter.
-     * param _s Signature `s` parameter.
-     * @return _success Whether or not the call returned (rather than reverted).
-     * @return _returndata Data returned by the call.
-     */
-    function execute(
-        bytes memory _transaction,
-        Lib_OVMCodec.EOASignatureType _signatureType,
-        uint8, // _v,
-        bytes32, // _r,
-        bytes32 // _s
-    )
-        override
-        public
-        returns (
-            bool _success,
-            bytes memory _returndata
-        )
-    {
-        bool isEthSign = _signatureType == Lib_OVMCodec.EOASignatureType.ETH_SIGNED_MESSAGE;
-        Lib_OVMCodec.EIP155Transaction memory decodedTx = Lib_OVMCodec.decodeEIP155Transaction(_transaction, isEthSign);
-
-        // Need to make sure that the transaction nonce is right.
-        Lib_SafeExecutionManagerWrapper.safeREQUIRE(
-            decodedTx.nonce == Lib_SafeExecutionManagerWrapper.safeGETNONCE(),
-            "Transaction nonce does not match the expected nonce."
-        );
-
-        // Contract creations are signalled by sending a transaction to the zero address.
-        if (decodedTx.to == address(0)) {
-            (address created, ) = Lib_SafeExecutionManagerWrapper.safeCREATE(
-                decodedTx.gasLimit,
-                decodedTx.data
-            );
-
-            // If the created address is the ZERO_ADDRESS then we know the deployment failed, though not why
-            return (created != address(0), abi.encode(created));
-        } else {
-            // We only want to bump the nonce for `ovmCALL` because `ovmCREATE` automatically bumps
-            // the nonce of the calling account. Normally an EOA would bump the nonce for both
-            // cases, but since this is a contract we'd end up bumping the nonce twice.
-            Lib_SafeExecutionManagerWrapper.safeINCREMENTNONCE();
-
-            return Lib_SafeExecutionManagerWrapper.safeCALL(
-                decodedTx.gasLimit,
-                decodedTx.to,
-                decodedTx.data
-            );
-        }
-    }
-
-    function qall(
-        uint256 _gasLimit,
-        address _to,
-        bytes memory _data
-    )
-        public
-        returns (
-            bool _success,
-            bytes memory _returndata
-        )
-    {
-        return Lib_SafeExecutionManagerWrapper.safeCALL(
-            _gasLimit,
-            _to,
-            _data
-        );
-    }
-}
diff --git a/packages/contracts/contracts/test-libraries/codec/TestLib_EIP155Tx.sol b/packages/contracts/contracts/test-libraries/codec/TestLib_EIP155Tx.sol
new file mode 100644
index 000000000000..6019b8695f8c
--- /dev/null
+++ b/packages/contracts/contracts/test-libraries/codec/TestLib_EIP155Tx.sol
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >0.5.0 <0.8.0;
+pragma experimental ABIEncoderV2;
+
+/* Library Imports */
+import { Lib_EIP155Tx } from "../../optimistic-ethereum/libraries/codec/Lib_EIP155Tx.sol";
+
+/**
+ * @title TestLib_EIP155Tx
+ */
+contract TestLib_EIP155Tx {
+    function decode(
+        bytes memory _encoded,
+        uint256 _chainId
+    )
+        public
+        pure
+        returns (
+            Lib_EIP155Tx.EIP155Tx memory
+        )
+    {
+        return Lib_EIP155Tx.decode(
+            _encoded,
+            _chainId
+        );
+    }
+
+    function encode(
+        Lib_EIP155Tx.EIP155Tx memory _transaction,
+        bool _includeSignature
+    )
+        public
+        pure
+        returns (
+            bytes memory
+        )
+    {
+        return Lib_EIP155Tx.encode(
+            _transaction,
+            _includeSignature
+        );
+    }
+
+    function hash(
+        Lib_EIP155Tx.EIP155Tx memory _transaction
+    )
+        public
+        pure
+        returns (
+            bytes32
+        )
+    {
+        return Lib_EIP155Tx.hash(
+            _transaction
+        );
+    }
+
+    function sender(
+        Lib_EIP155Tx.EIP155Tx memory _transaction
+    )
+        public
+        pure
+        returns (
+            address
+        )
+    {
+        return Lib_EIP155Tx.sender(
+            _transaction
+        );
+    }
+}
diff --git a/packages/contracts/contracts/test-libraries/codec/TestLib_OVMCodec.sol b/packages/contracts/contracts/test-libraries/codec/TestLib_OVMCodec.sol
index b9046ac8a776..9e96dd0cd800 100644
--- a/packages/contracts/contracts/test-libraries/codec/TestLib_OVMCodec.sol
+++ b/packages/contracts/contracts/test-libraries/codec/TestLib_OVMCodec.sol
@@ -10,19 +10,6 @@ import { Lib_OVMCodec } from "../../optimistic-ethereum/libraries/codec/Lib_OVMC
  */
 contract TestLib_OVMCodec {
 
-    function decodeEIP155Transaction(
-        bytes memory _transaction,
-        bool _isEthSignedMessage
-    )
-        public
-        pure
-        returns (
-            Lib_OVMCodec.EIP155Transaction memory _decoded
-        )
-    {
-        return Lib_OVMCodec.decodeEIP155Transaction(_transaction, _isEthSignedMessage);
-    }
-
     function encodeTransaction(
         Lib_OVMCodec.Transaction memory _transaction
     )
@@ -46,15 +33,4 @@ contract TestLib_OVMCodec {
     {
         return Lib_OVMCodec.hashTransaction(_transaction);
     }
-
-    function decompressEIP155Transaction(
-        bytes memory _transaction
-    )
-        public
-        returns (
-            Lib_OVMCodec.EIP155Transaction memory _decompressed
-        )
-    {
-        return Lib_OVMCodec.decompressEIP155Transaction(_transaction);
-    }
 }
diff --git a/packages/contracts/contracts/test-libraries/utils/TestLib_ECDSAUtils.sol b/packages/contracts/contracts/test-libraries/utils/TestLib_ECDSAUtils.sol
deleted file mode 100644
index 4b66bf7f0ec8..000000000000
--- a/packages/contracts/contracts/test-libraries/utils/TestLib_ECDSAUtils.sol
+++ /dev/null
@@ -1,33 +0,0 @@
-// SPDX-License-Identifier: MIT
-pragma solidity >0.5.0 <0.8.0;
-
-/* Library Imports */
-import { Lib_ECDSAUtils } from "../../optimistic-ethereum/libraries/utils/Lib_ECDSAUtils.sol";
-
-/**
- * @title TestLib_ECDSAUtils
- */
-contract TestLib_ECDSAUtils {
-
-    function recover(
-        bytes memory _message,
-        bool _isEthSignedMessage,
-        uint8 _v,
-        bytes32 _r,
-        bytes32 _s
-    )
-        public
-        pure
-        returns (
-            address _sender
-        )
-    {
-        return Lib_ECDSAUtils.recover(
-            _message,
-            _isEthSignedMessage,
-            _v,
-            _r,
-            _s
-        );
-    }
-}
diff --git a/packages/contracts/src/contract-deployment/config.ts b/packages/contracts/src/contract-deployment/config.ts
index 5ddfc87b88ef..64b662ec17bf 100644
--- a/packages/contracts/src/contract-deployment/config.ts
+++ b/packages/contracts/src/contract-deployment/config.ts
@@ -225,9 +225,6 @@ export const makeContractDeployConfig = async (
     OVM_ProxySequencerEntrypoint: {
       factory: getContractFactory('OVM_ProxySequencerEntrypoint'),
     },
-    mockOVM_ECDSAContractAccount: {
-      factory: getContractFactory('mockOVM_ECDSAContractAccount'),
-    },
     OVM_BondManager: {
       factory: getContractFactory('mockOVM_BondManager'),
       params: [AddressManager.address],
diff --git a/packages/contracts/test/contracts/OVM/accounts/OVM_ECDSAContractAccount.spec.ts b/packages/contracts/test/contracts/OVM/accounts/OVM_ECDSAContractAccount.spec.ts
index 9bb7fc5bd165..0189e9c57bc1 100644
--- a/packages/contracts/test/contracts/OVM/accounts/OVM_ECDSAContractAccount.spec.ts
+++ b/packages/contracts/test/contracts/OVM/accounts/OVM_ECDSAContractAccount.spec.ts
@@ -7,14 +7,7 @@ import { MockContract, smockit } from '@eth-optimism/smock'
 
 /* Internal Imports */
 import { NON_ZERO_ADDRESS } from '../../../helpers/constants'
-import {
-  serializeNativeTransaction,
-  signNativeTransaction,
-  DEFAULT_EIP155_TX,
-  serializeEthSignTransaction,
-  signEthSignMessage,
-  decodeSolidityError,
-} from '../../../helpers'
+import { DEFAULT_EIP155_TX, decodeSolidityError } from '../../../helpers'
 
 const callPredeploy = async (
   Helper_PredeployCaller: Contract,
@@ -41,10 +34,9 @@ const callPredeploy = async (
 
 describe('OVM_ECDSAContractAccount', () => {
   let wallet: Wallet
-  let badWallet: Wallet
   before(async () => {
     const provider = waffle.provider
-    ;[wallet, badWallet] = provider.getWallets()
+    ;[wallet] = provider.getWallets()
   })
 
   let Mock__OVM_ExecutionManager: MockContract
@@ -88,43 +80,14 @@ describe('OVM_ECDSAContractAccount', () => {
 
   describe('fallback()', () => {
     it(`should successfully execute an EIP155Transaction`, async () => {
-      const message = serializeNativeTransaction(DEFAULT_EIP155_TX)
-      const sig = await signNativeTransaction(wallet, DEFAULT_EIP155_TX)
+      const transaction = DEFAULT_EIP155_TX
+      const encodedTransaction = await wallet.signTransaction(transaction)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [
-          message,
-          0, // isEthSignedMessage
-          `0x${sig.v}`, //v
-          `0x${sig.r}`, //r
-          `0x${sig.s}`, //s
-        ]
-      )
-
-      // The ovmCALL is the 2nd call because the first call transfers the fee.
-      const ovmCALL: any = Mock__OVM_ExecutionManager.smocked.ovmCALL.calls[1]
-      expect(ovmCALL._address).to.equal(DEFAULT_EIP155_TX.to)
-      expect(ovmCALL._calldata).to.equal(DEFAULT_EIP155_TX.data)
-    })
-
-    it(`should successfully execute an ETHSignedTransaction`, async () => {
-      const message = serializeEthSignTransaction(DEFAULT_EIP155_TX)
-      const sig = await signEthSignMessage(wallet, DEFAULT_EIP155_TX)
-
-      await callPredeploy(
-        Helper_PredeployCaller,
-        OVM_ECDSAContractAccount,
-        'execute',
-        [
-          message,
-          1, //isEthSignedMessage
-          `0x${sig.v}`, //v
-          `0x${sig.r}`, //r
-          `0x${sig.s}`, //s
-        ]
+        [encodedTransaction]
       )
 
       // The ovmCALL is the 2nd call because the first call transfers the fee.
@@ -134,43 +97,33 @@ describe('OVM_ECDSAContractAccount', () => {
     })
 
     it(`should ovmCREATE if EIP155Transaction.to is zero address`, async () => {
-      const createTx = { ...DEFAULT_EIP155_TX, to: '' }
-      const message = serializeNativeTransaction(createTx)
-      const sig = await signNativeTransaction(wallet, createTx)
+      const transaction = { ...DEFAULT_EIP155_TX, to: '' }
+      const encodedTransaction = await wallet.signTransaction(transaction)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [
-          message,
-          0, //isEthSignedMessage
-          `0x${sig.v}`, //v
-          `0x${sig.r}`, //r
-          `0x${sig.s}`, //s
-        ]
+        [encodedTransaction]
       )
 
       const ovmCREATE: any =
         Mock__OVM_ExecutionManager.smocked.ovmCREATE.calls[0]
-      expect(ovmCREATE._bytecode).to.equal(createTx.data)
+      expect(ovmCREATE._bytecode).to.equal(transaction.data)
     })
 
     it(`should revert on invalid signature`, async () => {
-      const message = serializeNativeTransaction(DEFAULT_EIP155_TX)
-      const sig = await signNativeTransaction(badWallet, DEFAULT_EIP155_TX)
+      const transaction = DEFAULT_EIP155_TX
+      const encodedTransaction = ethers.utils.serializeTransaction(
+        transaction,
+        '0x' + '00'.repeat(65)
+      )
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [
-          message,
-          0, //isEthSignedMessage
-          `0x${sig.v}`, //v
-          `0x${sig.r}`, //r
-          `0x${sig.s}`, //s
-        ]
+        [encodedTransaction]
       )
       const ovmREVERT: any =
         Mock__OVM_ExecutionManager.smocked.ovmREVERT.calls[0]
@@ -180,24 +133,14 @@ describe('OVM_ECDSAContractAccount', () => {
     })
 
     it(`should revert on incorrect nonce`, async () => {
-      const alteredNonceTx = {
-        ...DEFAULT_EIP155_TX,
-        nonce: 99,
-      }
-      const message = serializeNativeTransaction(alteredNonceTx)
-      const sig = await signNativeTransaction(wallet, alteredNonceTx)
+      const transaction = { ...DEFAULT_EIP155_TX, nonce: 99 }
+      const encodedTransaction = await wallet.signTransaction(transaction)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [
-          message,
-          0, //isEthSignedMessage
-          `0x${sig.v}`, //v
-          `0x${sig.r}`, //r
-          `0x${sig.s}`, //s
-        ]
+        [encodedTransaction]
       )
       const ovmREVERT: any =
         Mock__OVM_ExecutionManager.smocked.ovmREVERT.calls[0]
@@ -207,52 +150,32 @@ describe('OVM_ECDSAContractAccount', () => {
     })
 
     it(`should revert on incorrect chainId`, async () => {
-      const alteredChainIdTx = {
-        ...DEFAULT_EIP155_TX,
-        chainId: 421,
-      }
-      const message = serializeNativeTransaction(alteredChainIdTx)
-      const sig = await signNativeTransaction(wallet, alteredChainIdTx)
+      const transaction = { ...DEFAULT_EIP155_TX, chainId: 421 }
+      const encodedTransaction = await wallet.signTransaction(transaction)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [
-          message,
-          0, //isEthSignedMessage
-          `0x${sig.v}`, //v
-          `0x${sig.r}`, //r
-          `0x${sig.s}`, //s
-        ]
+        [encodedTransaction]
       )
       const ovmREVERT: any =
         Mock__OVM_ExecutionManager.smocked.ovmREVERT.calls[0]
       expect(decodeSolidityError(ovmREVERT._data)).to.equal(
-        'Transaction chainId does not match expected OVM chainId.'
+        'OVM_ECDSAContractAccount: Transaction was signed with the wrong chain ID.'
       )
     })
 
     // TEMPORARY: Skip gas checks for minnet.
     it.skip(`should revert on insufficient gas`, async () => {
-      const alteredInsufficientGasTx = {
-        ...DEFAULT_EIP155_TX,
-        gasLimit: 200000000,
-      }
-      const message = serializeNativeTransaction(alteredInsufficientGasTx)
-      const sig = await signNativeTransaction(wallet, alteredInsufficientGasTx)
+      const transaction = { ...DEFAULT_EIP155_TX, gasLimit: 200000000 }
+      const encodedTransaction = await wallet.signTransaction(transaction)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [
-          message,
-          0, //isEthSignedMessage
-          `0x${sig.v}`, //v
-          `0x${sig.r}`, //r
-          `0x${sig.s}`, //s
-        ],
+        [encodedTransaction],
         40000000
       )
 
@@ -264,21 +187,16 @@ describe('OVM_ECDSAContractAccount', () => {
     })
 
     it(`should revert if fee is not transferred to the relayer`, async () => {
-      const message = serializeNativeTransaction(DEFAULT_EIP155_TX)
-      const sig = await signNativeTransaction(wallet, DEFAULT_EIP155_TX)
+      const transaction = DEFAULT_EIP155_TX
+      const encodedTransaction = await wallet.signTransaction(transaction)
+
       Mock__OVM_ExecutionManager.smocked.ovmCALL.will.return.with([false, '0x'])
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [
-          message,
-          0, //isEthSignedMessage
-          `0x${sig.v}`, //v
-          `0x${sig.r}`, //r
-          `0x${sig.s}`, //s
-        ],
+        [encodedTransaction],
         40000000
       )
 
diff --git a/packages/contracts/test/contracts/OVM/precompiles/OVM_SequencerEntrypoint.spec.ts b/packages/contracts/test/contracts/OVM/precompiles/OVM_SequencerEntrypoint.spec.ts
index 2979ad3bc33e..81bd75986c94 100644
--- a/packages/contracts/test/contracts/OVM/precompiles/OVM_SequencerEntrypoint.spec.ts
+++ b/packages/contracts/test/contracts/OVM/precompiles/OVM_SequencerEntrypoint.spec.ts
@@ -7,14 +7,7 @@ import { smockit, MockContract } from '@eth-optimism/smock'
 
 /* Internal Imports */
 import { getContractInterface } from '../../../../src'
-import {
-  encodeSequencerCalldata,
-  signNativeTransaction,
-  signEthSignMessage,
-  DEFAULT_EIP155_TX,
-  serializeNativeTransaction,
-  serializeEthSignTransaction,
-} from '../../../helpers'
+import { DEFAULT_EIP155_TX } from '../../../helpers'
 
 describe('OVM_SequencerEntrypoint', () => {
   let wallet: Wallet
@@ -55,128 +48,59 @@ describe('OVM_SequencerEntrypoint', () => {
   })
 
   describe('fallback()', async () => {
-    it('should call EIP155 if the transaction type is 0', async () => {
-      const calldata = await encodeSequencerCalldata(
-        wallet,
-        DEFAULT_EIP155_TX,
-        0
-      )
+    it('should call EIP155', async () => {
+      const transaction = DEFAULT_EIP155_TX
+      const encodedTransaction = await wallet.signTransaction(transaction)
+
       await Helper_PredeployCaller.callPredeploy(
         OVM_SequencerEntrypoint.address,
-        calldata
+        encodedTransaction
       )
 
-      const encodedTx = serializeNativeTransaction(DEFAULT_EIP155_TX)
-      const sig = await signNativeTransaction(wallet, DEFAULT_EIP155_TX)
-
       const expectedEOACalldata = getContractInterface(
         'OVM_ECDSAContractAccount'
-      ).encodeFunctionData('execute', [
-        encodedTx,
-        0, //isEthSignedMessage
-        `0x${sig.v}`, //v
-        `0x${sig.r}`, //r
-        `0x${sig.s}`, //s
-      ])
+      ).encodeFunctionData('execute', [encodedTransaction])
       const ovmCALL: any = Mock__OVM_ExecutionManager.smocked.ovmCALL.calls[0]
       expect(ovmCALL._address).to.equal(await wallet.getAddress())
       expect(ovmCALL._calldata).to.equal(expectedEOACalldata)
     })
 
-    it('should send correct calldata if tx is a create and the transaction type is 0', async () => {
-      const createTx = { ...DEFAULT_EIP155_TX, to: '' }
-      const calldata = await encodeSequencerCalldata(wallet, createTx, 0)
+    it('should send correct calldata if tx is a create', async () => {
+      const transaction = { ...DEFAULT_EIP155_TX, to: '' }
+      const encodedTransaction = await wallet.signTransaction(transaction)
+
       await Helper_PredeployCaller.callPredeploy(
         OVM_SequencerEntrypoint.address,
-        calldata
+        encodedTransaction
       )
 
-      const encodedTx = serializeNativeTransaction(createTx)
-      const sig = await signNativeTransaction(wallet, createTx)
-
       const expectedEOACalldata = getContractInterface(
         'OVM_ECDSAContractAccount'
-      ).encodeFunctionData('execute', [
-        encodedTx,
-        0, //isEthSignedMessage
-        `0x${sig.v}`, //v
-        `0x${sig.r}`, //r
-        `0x${sig.s}`, //s
-      ])
+      ).encodeFunctionData('execute', [encodedTransaction])
       const ovmCALL: any = Mock__OVM_ExecutionManager.smocked.ovmCALL.calls[0]
       expect(ovmCALL._address).to.equal(await wallet.getAddress())
       expect(ovmCALL._calldata).to.equal(expectedEOACalldata)
     })
 
-    for (let i = 0; i < 3; i += 2) {
-      it(`should call ovmCreateEOA when tx type is ${i} and ovmEXTCODESIZE returns 0`, async () => {
-        Mock__OVM_ExecutionManager.smocked.ovmEXTCODESIZE.will.return.with(0)
-        const calldata = await encodeSequencerCalldata(
-          wallet,
-          DEFAULT_EIP155_TX,
-          i
-        )
-        await Helper_PredeployCaller.callPredeploy(
-          OVM_SequencerEntrypoint.address,
-          calldata
-        )
-        const call: any =
-          Mock__OVM_ExecutionManager.smocked.ovmCREATEEOA.calls[0]
-        const eoaAddress = ethers.utils.recoverAddress(call._messageHash, {
-          v: call._v + 27,
-          r: call._r,
-          s: call._s,
-        })
-        expect(eoaAddress).to.equal(await wallet.getAddress())
-      })
-    }
+    it(`should call ovmCreateEOA when ovmEXTCODESIZE returns 0`, async () => {
+      Mock__OVM_ExecutionManager.smocked.ovmEXTCODESIZE.will.return.with(0)
+
+      const transaction = DEFAULT_EIP155_TX
+      const encodedTransaction = await wallet.signTransaction(transaction)
 
-    it('should submit ETHSignedTypedData if TransactionType is 2', async () => {
-      const calldata = await encodeSequencerCalldata(
-        wallet,
-        DEFAULT_EIP155_TX,
-        2
-      )
       await Helper_PredeployCaller.callPredeploy(
         OVM_SequencerEntrypoint.address,
-        calldata
+        encodedTransaction
       )
 
-      const encodedTx = serializeEthSignTransaction(DEFAULT_EIP155_TX)
-      const sig = await signEthSignMessage(wallet, DEFAULT_EIP155_TX)
-
-      const expectedEOACalldata = getContractInterface(
-        'OVM_ECDSAContractAccount'
-      ).encodeFunctionData('execute', [
-        encodedTx,
-        1, //isEthSignedMessage
-        `0x${sig.v}`, //v
-        `0x${sig.r}`, //r
-        `0x${sig.s}`, //s
-      ])
-      const ovmCALL: any = Mock__OVM_ExecutionManager.smocked.ovmCALL.calls[0]
-      expect(ovmCALL._address).to.equal(await wallet.getAddress())
-      expect(ovmCALL._calldata).to.equal(expectedEOACalldata)
-    })
-
-    it('should revert if TransactionType is >2', async () => {
-      const calldata = '0x03'
-      await expect(
-        Helper_PredeployCaller.callPredeploy(
-          OVM_SequencerEntrypoint.address,
-          calldata
-        )
-      ).to.be.reverted
-    })
+      const call: any = Mock__OVM_ExecutionManager.smocked.ovmCREATEEOA.calls[0]
+      const eoaAddress = ethers.utils.recoverAddress(call._messageHash, {
+        v: call._v + 27,
+        r: call._r,
+        s: call._s,
+      })
 
-    it('should revert if TransactionType is 1', async () => {
-      const calldata = '0x01'
-      await expect(
-        Helper_PredeployCaller.callPredeploy(
-          OVM_SequencerEntrypoint.address,
-          calldata
-        )
-      ).to.be.reverted
+      expect(eoaAddress).to.equal(await wallet.getAddress())
     })
   })
 })
diff --git a/packages/contracts/test/contracts/libraries/codec/Lib_EIP155Tx.ts b/packages/contracts/test/contracts/libraries/codec/Lib_EIP155Tx.ts
new file mode 100644
index 000000000000..021f14edcb19
--- /dev/null
+++ b/packages/contracts/test/contracts/libraries/codec/Lib_EIP155Tx.ts
@@ -0,0 +1,15 @@
+/* tslint:disable:no-empty */
+import '../../../setup'
+
+/* Internal Imports */
+import { Lib_EIP155Tx_TEST_JSON } from '../../../data'
+import { runJsonTest } from '../../../helpers'
+
+// Currently running tests from here:
+// https://github.com/ethereumjs/ethereumjs-tx/blob/master/test/ttTransactionTestEip155VitaliksTests.json
+
+describe('Lib_EIP155Tx', () => {
+  describe('JSON tests', () => {
+    runJsonTest('TestLib_EIP155Tx', Lib_EIP155Tx_TEST_JSON)
+  })
+})
diff --git a/packages/contracts/test/contracts/libraries/utils/Lib_ECDSAUtils.spec.ts b/packages/contracts/test/contracts/libraries/utils/Lib_ECDSAUtils.spec.ts
deleted file mode 100644
index baf3c5a999b2..000000000000
--- a/packages/contracts/test/contracts/libraries/utils/Lib_ECDSAUtils.spec.ts
+++ /dev/null
@@ -1,9 +0,0 @@
-/* Internal Imports */
-import { Lib_ECDSAUtils_TEST_JSON } from '../../../data'
-import { runJsonTest } from '../../../helpers'
-
-describe('Lib_ECDSAUtils', () => {
-  describe('JSON tests', () => {
-    runJsonTest('TestLib_ECDSAUtils', Lib_ECDSAUtils_TEST_JSON)
-  })
-})
diff --git a/packages/contracts/test/data/index.ts b/packages/contracts/test/data/index.ts
index 8a4a1f7e65b8..5c9103f5c2d5 100644
--- a/packages/contracts/test/data/index.ts
+++ b/packages/contracts/test/data/index.ts
@@ -2,8 +2,8 @@ export { tests as Lib_RLPWriter_TEST_JSON } from './json/libraries/rlp/Lib_RLPWr
 export { tests as Lib_RLPReader_TEST_JSON } from './json/libraries/rlp/Lib_RLPReader.test.json'
 export { tests as Lib_Bytes32Utils_TEST_JSON } from './json/libraries/utils/Lib_Bytes32Utils.test.json'
 export { tests as Lib_BytesUtils_TEST_JSON } from './json/libraries/utils/Lib_BytesUtils.test.json'
-export { tests as Lib_ECDSAUtils_TEST_JSON } from './json/libraries/utils/Lib_ECDSAUtils.test.json'
 export { tests as Lib_MerkleTrie_TEST_JSON } from './json/libraries/trie/Lib_MerkleTrie.test.json'
+export { tests as Lib_EIP155Tx_TEST_JSON } from './json/libraries/codec/Lib_EIP155Tx.test.json'
 export { tests as Lib_OVMCodec_TEST_JSON } from './json/libraries/codec/Lib_OVMCodec.test.json'
 export { tests as CREATE2_TEST_JSON } from './json/create2.test.json'
 export { tests as SAFETY_CHECKER_TEST_JSON } from './json/safety-checker.test.json'
diff --git a/packages/contracts/test/data/json/libraries/codec/Lib_EIP155Tx.test.json b/packages/contracts/test/data/json/libraries/codec/Lib_EIP155Tx.test.json
new file mode 100644
index 000000000000..a7536ad4fa3b
--- /dev/null
+++ b/packages/contracts/test/data/json/libraries/codec/Lib_EIP155Tx.test.json
@@ -0,0 +1,725 @@
+{
+    "tests": {
+        "decode": {
+            "vitalik test 0": {
+                "in": [
+                    "0xf864808504a817c800825208943535353535353535353535353535353535353535808025a0044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116da0044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x00",
+                        "0x04a817c800",
+                        "0x5208",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x00",
+                        "0x",
+                        "0x25",
+                        "0x044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
+                        "0x044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            },
+            "vitalik test 1": {
+                "in": [
+                    "0xf867088504a817c8088302e2489435353535353535353535353535353535353535358202008025a064b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c12a064b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c10",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x08",
+                        "0x04a817c808",
+                        "0x02e248",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x0200",
+                        "0x",
+                        "0x25",
+                        "0x64b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c12",
+                        "0x64b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c10",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            },
+            "vitalik test 2": {
+                "in": [
+                    "0xf867098504a817c809830334509435353535353535353535353535353535353535358202d98025a052f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afba052f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x09",
+                        "0x04a817c809",
+                        "0x033450",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x02d9",
+                        "0x",
+                        "0x25",
+                        "0x52f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb",
+                        "0x52f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            },
+            "vitalik test 3": {
+                "in": [
+                    "0xf864018504a817c80182a410943535353535353535353535353535353535353535018025a0489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bcaa0489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bc6",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x01",
+                        "0x04a817c801",
+                        "0xa410",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x01",
+                        "0x",
+                        "0x25",
+                        "0x489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bca",
+                        "0x489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bc6",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            },
+            "vitalik test 4": {
+                "in": [
+                    "0xf864028504a817c80282f618943535353535353535353535353535353535353535088025a02d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5a02d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x02",
+                        "0x04a817c802",
+                        "0xf618",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x08",
+                        "0x",
+                        "0x25",
+                        "0x2d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5",
+                        "0x2d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            },
+            "vitalik test 5": {
+                "in": [
+                    "0xf865038504a817c803830148209435353535353535353535353535353535353535351b8025a02a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4e0a02a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4de",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x03",
+                        "0x04a817c803",
+                        "0x014820",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x1b",
+                        "0x",
+                        "0x25",
+                        "0x2a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4e0",
+                        "0x2a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4de",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            },
+            "vitalik test 6": {
+                "in": [
+                    "0xf865048504a817c80483019a28943535353535353535353535353535353535353535408025a013600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c063a013600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c060",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x04",
+                        "0x04a817c804",
+                        "0x019a28",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x40",
+                        "0x",
+                        "0x25",
+                        "0x13600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c063",
+                        "0x13600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c060",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            },
+            "vitalik test 7": {
+                "in": [
+                    "0xf865058504a817c8058301ec309435353535353535353535353535353535353535357d8025a04eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1a04eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x05",
+                        "0x04a817c805",
+                        "0x01ec30",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x7d",
+                        "0x",
+                        "0x25",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            },
+            "vitalik test 8": {
+                "in": [
+                    "0xf865058504a817c8058301ec309435353535353535353535353535353535353535357d8025a04eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1a04eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x05",
+                        "0x04a817c805",
+                        "0x01ec30",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x7d",
+                        "0x",
+                        "0x25",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            },
+            "vitalik test 9": {
+                "in": [
+                    "0xf866068504a817c80683023e3894353535353535353535353535353535353535353581d88025a06455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2fa06455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2d",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x06",
+                        "0x04a817c806",
+                        "0x023e38",
+                        "0x3535353535353535353535353535353535353535",
+                        "0xd8",
+                        "0x",
+                        "0x25",
+                        "0x6455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2f",
+                        "0x6455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2d",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            },
+            "vitalik test 10": {
+                "in": [
+                    "0xf867078504a817c807830290409435353535353535353535353535353535353535358201578025a052f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021a052f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021",
+                    1
+                ],
+                "out": [
+                    [
+                        "0x07",
+                        "0x04a817c807",
+                        "0x029040",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x0157",
+                        "0x",
+                        "0x25",
+                        "0x52f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021",
+                        "0x52f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ]
+            }
+        },
+        "encode": {
+            "vitalik test 0": {
+                "in": [
+                    [
+                        "0x00",
+                        "0x04a817c800",
+                        "0x5208",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x00",
+                        "0x",
+                        "0x25",
+                        "0x044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
+                        "0x044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf864808504a817c800825208943535353535353535353535353535353535353535808025a0044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116da0044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d"
+                ]
+            },
+            "vitalik test 1": {
+                "in": [
+                    [
+                        "0x08",
+                        "0x04a817c808",
+                        "0x02e248",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x0200",
+                        "0x",
+                        "0x25",
+                        "0x64b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c12",
+                        "0x64b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c10",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf867088504a817c8088302e2489435353535353535353535353535353535353535358202008025a064b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c12a064b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c10"
+                ]
+            },
+            "vitalik test 2": {
+                "in": [
+                    [
+                        "0x09",
+                        "0x04a817c809",
+                        "0x033450",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x02d9",
+                        "0x",
+                        "0x25",
+                        "0x52f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb",
+                        "0x52f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf867098504a817c809830334509435353535353535353535353535353535353535358202d98025a052f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afba052f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb"
+                ]
+            },
+            "vitalik test 3": {
+                "in": [
+                    [
+                        "0x01",
+                        "0x04a817c801",
+                        "0xa410",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x01",
+                        "0x",
+                        "0x25",
+                        "0x489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bca",
+                        "0x489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bc6",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf864018504a817c80182a410943535353535353535353535353535353535353535018025a0489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bcaa0489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bc6"
+                ]
+            },
+            "vitalik test 4": {
+                "in": [
+                    [
+                        "0x02",
+                        "0x04a817c802",
+                        "0xf618",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x08",
+                        "0x",
+                        "0x25",
+                        "0x2d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5",
+                        "0x2d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf864028504a817c80282f618943535353535353535353535353535353535353535088025a02d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5a02d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5"
+                ]
+            },
+            "vitalik test 5": {
+                "in": [
+                    [
+                        "0x03",
+                        "0x04a817c803",
+                        "0x014820",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x1b",
+                        "0x",
+                        "0x25",
+                        "0x2a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4e0",
+                        "0x2a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4de",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf865038504a817c803830148209435353535353535353535353535353535353535351b8025a02a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4e0a02a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4de"
+                ]
+            },
+            "vitalik test 6": {
+                "in": [
+                    [
+                        "0x04",
+                        "0x04a817c804",
+                        "0x019a28",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x40",
+                        "0x",
+                        "0x25",
+                        "0x13600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c063",
+                        "0x13600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c060",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf865048504a817c80483019a28943535353535353535353535353535353535353535408025a013600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c063a013600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c060"
+                ]
+            },
+            "vitalik test 7": {
+                "in": [
+                    [
+                        "0x05",
+                        "0x04a817c805",
+                        "0x01ec30",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x7d",
+                        "0x",
+                        "0x25",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf865058504a817c8058301ec309435353535353535353535353535353535353535357d8025a04eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1a04eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1"
+                ]
+            },
+            "vitalik test 8": {
+                "in": [
+                    [
+                        "0x05",
+                        "0x04a817c805",
+                        "0x01ec30",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x7d",
+                        "0x",
+                        "0x25",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf865058504a817c8058301ec309435353535353535353535353535353535353535357d8025a04eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1a04eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1"
+                ]
+            },
+            "vitalik test 9": {
+                "in": [
+                    [
+                        "0x06",
+                        "0x04a817c806",
+                        "0x023e38",
+                        "0x3535353535353535353535353535353535353535",
+                        "0xd8",
+                        "0x",
+                        "0x25",
+                        "0x6455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2f",
+                        "0x6455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2d",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf866068504a817c80683023e3894353535353535353535353535353535353535353581d88025a06455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2fa06455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2d"
+                ]
+            },
+            "vitalik test 10": {
+                "in": [
+                    [
+                        "0x07",
+                        "0x04a817c807",
+                        "0x029040",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x0157",
+                        "0x",
+                        "0x25",
+                        "0x52f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021",
+                        "0x52f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021",
+                        "0x01",
+                        "0x00",
+                        false
+                    ],
+                    true
+                ],
+                "out": [
+                    "0xf867078504a817c807830290409435353535353535353535353535353535353535358201578025a052f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021a052f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021"
+                ]
+            }
+        },
+        "sender": {
+            "vitalik test 0": {
+                "in": [
+                    [
+                        "0x00",
+                        "0x04a817c800",
+                        "0x5208",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x00",
+                        "0x",
+                        "0x25",
+                        "0x044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
+                        "0x044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0xf0f6f18bca1b28cd68e4357452947e021241e9ce"
+                ]
+            },
+            "vitalik test 1": {
+                "in": [
+                    [
+                        "0x08",
+                        "0x04a817c808",
+                        "0x02e248",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x0200",
+                        "0x",
+                        "0x25",
+                        "0x64b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c12",
+                        "0x64b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c10",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0x9bddad43f934d313c2b79ca28a432dd2b7281029"
+                ]
+            },
+            "vitalik test 2": {
+                "in": [
+                    [
+                        "0x09",
+                        "0x04a817c809",
+                        "0x033450",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x02d9",
+                        "0x",
+                        "0x25",
+                        "0x52f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb",
+                        "0x52f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0x3c24d7329e92f84f08556ceb6df1cdb0104ca49f"
+                ]
+            },
+            "vitalik test 3": {
+                "in": [
+                    [
+                        "0x01",
+                        "0x04a817c801",
+                        "0xa410",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x01",
+                        "0x",
+                        "0x25",
+                        "0x489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bca",
+                        "0x489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bc6",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0x23ef145a395ea3fa3deb533b8a9e1b4c6c25d112"
+                ]
+            },
+            "vitalik test 4": {
+                "in": [
+                    [
+                        "0x02",
+                        "0x04a817c802",
+                        "0xf618",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x08",
+                        "0x",
+                        "0x25",
+                        "0x2d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5",
+                        "0x2d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0x2e485e0c23b4c3c542628a5f672eeab0ad4888be"
+                ]
+            },
+            "vitalik test 5": {
+                "in": [
+                    [
+                        "0x03",
+                        "0x04a817c803",
+                        "0x014820",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x1b",
+                        "0x",
+                        "0x25",
+                        "0x2a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4e0",
+                        "0x2a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4de",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0x82a88539669a3fd524d669e858935de5e5410cf0"
+                ]
+            },
+            "vitalik test 6": {
+                "in": [
+                    [
+                        "0x04",
+                        "0x04a817c804",
+                        "0x019a28",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x40",
+                        "0x",
+                        "0x25",
+                        "0x13600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c063",
+                        "0x13600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c060",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0xf9358f2538fd5ccfeb848b64a96b743fcc930554"
+                ]
+            },
+            "vitalik test 7": {
+                "in": [
+                    [
+                        "0x05",
+                        "0x04a817c805",
+                        "0x01ec30",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x7d",
+                        "0x",
+                        "0x25",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0xa8f7aba377317440bc5b26198a363ad22af1f3a4"
+                ]
+            },
+            "vitalik test 8": {
+                "in": [
+                    [
+                        "0x05",
+                        "0x04a817c805",
+                        "0x01ec30",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x7d",
+                        "0x",
+                        "0x25",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0xa8f7aba377317440bc5b26198a363ad22af1f3a4"
+                ]
+            },
+            "vitalik test 9": {
+                "in": [
+                    [
+                        "0x06",
+                        "0x04a817c806",
+                        "0x023e38",
+                        "0x3535353535353535353535353535353535353535",
+                        "0xd8",
+                        "0x",
+                        "0x25",
+                        "0x6455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2f",
+                        "0x6455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2d",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0xf1f571dc362a0e5b2696b8e775f8491d3e50de35"
+                ]
+            },
+            "vitalik test 10": {
+                "in": [
+                    [
+                        "0x07",
+                        "0x04a817c807",
+                        "0x029040",
+                        "0x3535353535353535353535353535353535353535",
+                        "0x0157",
+                        "0x",
+                        "0x25",
+                        "0x52f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021",
+                        "0x52f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021",
+                        "0x01",
+                        "0x00",
+                        false
+                    ]
+                ],
+                "out": [
+                    "0xd37922162ab7cea97c97a87551ed02c9a38b7332"
+                ]
+            }
+        }
+    }
+}
diff --git a/packages/contracts/test/data/json/libraries/codec/Lib_OVMCodec.test.json b/packages/contracts/test/data/json/libraries/codec/Lib_OVMCodec.test.json
index b442f4e07c8c..a55ce0122c21 100644
--- a/packages/contracts/test/data/json/libraries/codec/Lib_OVMCodec.test.json
+++ b/packages/contracts/test/data/json/libraries/codec/Lib_OVMCodec.test.json
@@ -1,22 +1,4 @@
 {
     "tests": {
-        "decompressEIP155Transaction": {
-            "decompression": {
-                "in": [
-                    "0x0001f4000064000064121212121212121212121212121212121212121299999999999999999999"
-                ],
-                "out": [
-                    [
-                        100,
-                        100000000,
-                        500,
-                        "0x1212121212121212121212121212121212121212",
-                        0,
-                        "0x99999999999999999999",
-                        420
-                    ]
-                ]
-            }
-        }
     }
 }
diff --git a/packages/contracts/test/data/json/libraries/utils/Lib_ECDSAUtils.test.json b/packages/contracts/test/data/json/libraries/utils/Lib_ECDSAUtils.test.json
deleted file mode 100644
index 40f15819442f..000000000000
--- a/packages/contracts/test/data/json/libraries/utils/Lib_ECDSAUtils.test.json
+++ /dev/null
@@ -1,126 +0,0 @@
-{
-    "tests": {
-        "recover": {
-            "standard hash, valid signature": {
-                "in": [
-                    "0xf83d80808094121212121212121212121212121212121212121280a0bc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a6c8080",
-                    false,
-                    "0x01",
-                    "0x057bf1c0edf0a9002a79f8c9b39683f6453a18e73e02364270a2b6ee8117f11a",
-                    "0x5f8181365a222c7b05a84c29a29754e6a925952d3bf4bd65a6259ef37ee048e3"
-                ],
-                "out": [
-                    "0x17ec8597ff92C3F44523bDc65BF0f1bE632917ff"
-                ]
-            },
-            "standard hash, invalid v parameter": {
-                "in": [
-                    "0xf83d80808094121212121212121212121212121212121212121280a0bc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a6c8080",
-                    false,
-                    "0xfc",
-                    "0x057bf1c0edf0a9002a79f8c9b39683f6453a18e73e02364270a2b6ee8117f11a",
-                    "0x5f8181365a222c7b05a84c29a29754e6a925952d3bf4bd65a6259ef37ee048e3"
-                ],
-                "out": [
-                    "0x0000000000000000000000000000000000000000"
-                ]
-            },
-            "standard hash, invalid r parameter": {
-                "in": [
-                    "0xf83d80808094121212121212121212121212121212121212121280a0bc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a6c8080",
-                    false,
-                    "0x01",
-                    "0x0000000000000000000000000000000000000000000000000000000000000000",
-                    "0x5f8181365a222c7b05a84c29a29754e6a925952d3bf4bd65a6259ef37ee048e3"
-                ],
-                "out": [
-                    "0x0000000000000000000000000000000000000000"
-                ]
-            },
-            "standard hash, invalid s parameter": {
-                "in": [
-                    "0xf83d80808094121212121212121212121212121212121212121280a0bc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a6c8080",
-                    false,
-                    "0x01",
-                    "0x057bf1c0edf0a9002a79f8c9b39683f6453a18e73e02364270a2b6ee8117f11a",
-                    "0x0000000000000000000000000000000000000000000000000000000000000000"
-                ],
-                "out": [
-                    "0x0000000000000000000000000000000000000000"
-                ]
-            },
-            "standard hash, invalid message": {
-                "in": [
-                    "0x0000000000000000000000000000000000000000000000000000000000000000",
-                    false,
-                    "0x01",
-                    "0x057bf1c0edf0a9002a79f8c9b39683f6453a18e73e02364270a2b6ee8117f11a",
-                    "0x5f8181365a222c7b05a84c29a29754e6a925952d3bf4bd65a6259ef37ee048e3"
-                ],
-                "out": [
-                    "0x1397890fcfC2D7563Aa01cE93A217b9809D3447B"
-                ]
-            },
-            "eth signed message hash, valid signature": {
-                "in": [
-                    "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",
-                    true,
-                    "0x01",
-                    "0xe5a2edb71b6d76a8aacd59467d3063fd455ca13a4e9cb57da6f25849d40e4e2a",
-                    "0x5465373d68d521845e3ffd2baf4c51f3d21c990914c09490b32ffc0b322dbf98"
-                ],
-                "out": [
-                    "0x17ec8597ff92C3F44523bDc65BF0f1bE632917ff"
-                ]
-            },
-            "eth signed message hash, invalid v parameter": {
-                "in": [
-                    "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",
-                    true,
-                    "0x1c",
-                    "0xe5a2edb71b6d76a8aacd59467d3063fd455ca13a4e9cb57da6f25849d40e4e2a",
-                    "0x5465373d68d521845e3ffd2baf4c51f3d21c990914c09490b32ffc0b322dbf98"
-                ],
-                "out": [
-                    "0x0000000000000000000000000000000000000000"
-                ]
-            },
-            "eth signed message hash, invalid r parameter": {
-                "in": [
-                    "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",
-                    true,
-                    "0x01",
-                    "0x0000000000000000000000000000000000000000000000000000000000000000",
-                    "0x5465373d68d521845e3ffd2baf4c51f3d21c990914c09490b32ffc0b322dbf98"
-                ],
-                "out": [
-                    "0x0000000000000000000000000000000000000000"
-                ]
-            },
-            "eth signed message hash, invalid s parameter": {
-                "in": [
-                    "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",
-                    true,
-                    "0x01",
-                    "0xe5a2edb71b6d76a8aacd59467d3063fd455ca13a4e9cb57da6f25849d40e4e2a",
-                    "0x0000000000000000000000000000000000000000000000000000000000000000"
-                ],
-                "out": [
-                    "0x0000000000000000000000000000000000000000"
-                ]
-            },
-            "eth signed message hash, invalid message": {
-                "in": [
-                    "0x0000000000000000000000000000000000000000000000000000000000000000",
-                    true,
-                    "0x01",
-                    "0xe5a2edb71b6d76a8aacd59467d3063fd455ca13a4e9cb57da6f25849d40e4e2a",
-                    "0x5465373d68d521845e3ffd2baf4c51f3d21c990914c09490b32ffc0b322dbf98"
-                ],
-                "out": [
-                    "0xf8bd1421f9D28C8F58f33B25a6faB16F3f89b749"
-                ]
-            }
-        }
-    }
-}
diff --git a/packages/contracts/test/helpers/codec/encoding.ts b/packages/contracts/test/helpers/codec/encoding.ts
index f7e16531fcd6..869e4feffca0 100644
--- a/packages/contracts/test/helpers/codec/encoding.ts
+++ b/packages/contracts/test/helpers/codec/encoding.ts
@@ -1,9 +1,5 @@
 /* External Imports */
 import { ethers } from 'hardhat'
-import { constants, Wallet } from 'ethers'
-
-/* Internal Imports */
-import { remove0x, fromHexString } from '@eth-optimism/core-utils'
 
 export interface EIP155Transaction {
   nonce: number
@@ -37,115 +33,3 @@ export const getRawSignedComponents = (signed: string): any[] => {
 export const getSignedComponents = (signed: string): any[] => {
   return ethers.utils.RLP.decode(signed).slice(-3)
 }
-
-export const encodeCompactTransaction = (transaction: any): string => {
-  const nonce = ethers.utils.zeroPad(transaction.nonce, 3)
-  const gasLimit = ethers.utils.zeroPad(transaction.gasLimit, 3)
-  if (transaction.gasPrice % 1000000 !== 0)
-    throw Error('gas price must be a multiple of 1000000')
-  const compressedGasPrice: any = transaction.gasPrice / 1000000
-  const gasPrice = ethers.utils.zeroPad(compressedGasPrice, 3)
-  const to = !transaction.to.length
-    ? fromHexString(constants.AddressZero)
-    : fromHexString(transaction.to)
-  const data = fromHexString(transaction.data)
-
-  return Buffer.concat([
-    Buffer.from(gasLimit),
-    Buffer.from(gasPrice),
-    Buffer.from(nonce),
-    Buffer.from(to),
-    data,
-  ]).toString('hex')
-}
-
-export const serializeEthSignTransaction = (
-  transaction: EIP155Transaction
-): string => {
-  return ethers.utils.defaultAbiCoder.encode(
-    ['uint256', 'uint256', 'uint256', 'uint256', 'address', 'bytes'],
-    [
-      transaction.nonce,
-      transaction.gasLimit,
-      transaction.gasPrice,
-      transaction.chainId,
-      transaction.to,
-      transaction.data,
-    ]
-  )
-}
-
-export const serializeNativeTransaction = (
-  transaction: EIP155Transaction
-): string => {
-  return ethers.utils.serializeTransaction(transaction)
-}
-
-export const signEthSignMessage = async (
-  wallet: Wallet,
-  transaction: EIP155Transaction
-): Promise<SignatureParameters> => {
-  const serializedTransaction = serializeEthSignTransaction(transaction)
-  const transactionHash = ethers.utils.keccak256(serializedTransaction)
-  const transactionHashBytes = ethers.utils.arrayify(transactionHash)
-  const transactionSignature = await wallet.signMessage(transactionHashBytes)
-
-  const messageHash = ethers.utils.hashMessage(transactionHashBytes)
-  const [v, r, s] = getRawSignedComponents(transactionSignature).map(
-    (component) => {
-      return remove0x(component)
-    }
-  )
-  return {
-    messageHash,
-    v: '0' + (parseInt(v, 16) - 27),
-    r,
-    s,
-  }
-}
-
-export const signNativeTransaction = async (
-  wallet: Wallet,
-  transaction: EIP155Transaction
-): Promise<SignatureParameters> => {
-  const serializedTransaction = serializeNativeTransaction(transaction)
-  const transactionSignature = await wallet.signTransaction(transaction)
-
-  const messageHash = ethers.utils.keccak256(serializedTransaction)
-  const [v, r, s] = getSignedComponents(transactionSignature).map(
-    (component) => {
-      return remove0x(component)
-    }
-  )
-  return {
-    messageHash,
-    v: '0' + (parseInt(v, 16) - transaction.chainId * 2 - 8 - 27),
-    r,
-    s,
-  }
-}
-
-export const signTransaction = async (
-  wallet: Wallet,
-  transaction: EIP155Transaction,
-  transactionType: number
-): Promise<SignatureParameters> => {
-  return transactionType === 2
-    ? signEthSignMessage(wallet, transaction) //ETH Signed tx
-    : signNativeTransaction(wallet, transaction) //Create EOA tx or EIP155 tx
-}
-
-export const encodeSequencerCalldata = async (
-  wallet: Wallet,
-  transaction: EIP155Transaction,
-  transactionType: number
-) => {
-  const sig = await signTransaction(wallet, transaction, transactionType)
-  const encodedTransaction = encodeCompactTransaction(transaction)
-  const dataPrefix = `0x0${transactionType}${sig.r}${sig.s}${sig.v}`
-  const calldata =
-    transactionType === 1
-      ? `${dataPrefix}${remove0x(sig.messageHash)}` // Create EOA tx
-      : `${dataPrefix}${encodedTransaction}` // EIP155 tx or ETH Signed Tx
-  return calldata
-}
diff --git a/packages/contracts/test/helpers/test-runner/json-test-runner.ts b/packages/contracts/test/helpers/test-runner/json-test-runner.ts
index 0380ee849f06..d32626835f5f 100644
--- a/packages/contracts/test/helpers/test-runner/json-test-runner.ts
+++ b/packages/contracts/test/helpers/test-runner/json-test-runner.ts
@@ -4,10 +4,16 @@ import { expect } from '../../setup'
 import { ethers } from 'hardhat'
 import { Contract, BigNumber } from 'ethers'
 
-const bigNumberify = (arr) => {
+const bnRegex = /^\d+n$/gm
+
+const bigNumberify = (arr: any[]) => {
   return arr.map((el: any) => {
     if (typeof el === 'number') {
       return BigNumber.from(el)
+    } else if (typeof el === 'string' && bnRegex.test(el)) {
+      return BigNumber.from(el.slice(0, el.length - 1))
+    } else if (typeof el === 'string' && el.length > 2 && el.startsWith('0x')) {
+      return BigNumber.from(el.toLowerCase())
     } else if (Array.isArray(el)) {
       return bigNumberify(el)
     } else {
@@ -31,7 +37,7 @@ export const runJsonTest = (contractName: string, json: any): void => {
               .reverted
           } else {
             expect(
-              await contract.functions[functionName](...test.in)
+              bigNumberify(await contract.functions[functionName](...test.in))
             ).to.deep.equal(bigNumberify(test.out))
           }
         })

From d071f0f415c9e2aafe8abe13b8bfa00a8e5ad57e Mon Sep 17 00:00:00 2001
From: Maurelian <maurelian@protonmail.ch>
Date: Thu, 15 Apr 2021 19:29:30 -0400
Subject: [PATCH 4/7] fix hardcoded test val

---
 .../OVM/execution/OVM_ExecutionManager/nuisance-gas.spec.ts     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/contracts/test/contracts/OVM/execution/OVM_ExecutionManager/nuisance-gas.spec.ts b/packages/contracts/test/contracts/OVM/execution/OVM_ExecutionManager/nuisance-gas.spec.ts
index 821ee3fd9b82..0b60db0926ca 100644
--- a/packages/contracts/test/contracts/OVM/execution/OVM_ExecutionManager/nuisance-gas.spec.ts
+++ b/packages/contracts/test/contracts/OVM/execution/OVM_ExecutionManager/nuisance-gas.spec.ts
@@ -188,7 +188,7 @@ const test_nuisanceGas: TestDefinition = {
             // This is because there is natural gas consumption between the ovmCALL(GAS/2) and ovmCREATE, which allots nuisance gas via _getNuisanceGasLimit.
             // This means that the ovmCREATE exception, DOES consumes all nuisance gas allotted, but that allotment
             // is less than the full OVM_TX_GAS_LIMIT / 2 which is alloted to the parent ovmCALL.
-            nuisanceGasLeft: 4184829,
+            nuisanceGasLeft: 4185958,
           },
         },
       },

From 1e3276d2134807793777ad2f947a90449f8fb3e2 Mon Sep 17 00:00:00 2001
From: Maurelian <maurelian@protonmail.ch>
Date: Thu, 15 Apr 2021 19:39:01 -0400
Subject: [PATCH 5/7] chore: add changeset

---
 .changeset/ten-baboons-compete.md | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 .changeset/ten-baboons-compete.md

diff --git a/.changeset/ten-baboons-compete.md b/.changeset/ten-baboons-compete.md
new file mode 100644
index 000000000000..c7acd3945d47
--- /dev/null
+++ b/.changeset/ten-baboons-compete.md
@@ -0,0 +1,8 @@
+---
+"@eth-optimism/contracts": minor
+---
+
+- Remove ETH_SIGNED_MESSAGE and standardize on EIP-155 messages
+- Reduce nonce size to uint64
+- Ban ovmCALLER opcode when it would return ZERO
+- Add value transfer in OVM_ECDSAContractAccount

From 3855dcd3a9ed790b33b1edca3d5d33ebf5a220b6 Mon Sep 17 00:00:00 2001
From: Maurelian <maurelian@protonmail.ch>
Date: Thu, 15 Apr 2021 22:02:19 -0400
Subject: [PATCH 6/7] Revert "Merge branch 'master' into
 feat/standard-rlp-transaction"

This reverts commit af9f9a65a452755f64cd33999426c8238ed081c7.
---
 .../OVM/accounts/OVM_ECDSAContractAccount.sol |  52 +-
 .../OVM/accounts/OVM_ProxyEOA.sol             |   2 +
 .../predeploys/OVM_SequencerEntrypoint.sol    | 118 ++-
 .../accounts/iOVM_ECDSAContractAccount.sol    |  16 +-
 .../libraries/codec/Lib_EIP155Tx.sol          | 196 -----
 .../libraries/codec/Lib_OVMCodec.sol          | 137 ++++
 .../libraries/rlp/Lib_RLPWriter.sol           |  17 -
 .../libraries/utils/Lib_ECDSAUtils.sol        |  98 +++
 .../accounts/mockOVM_ECDSAContractAccount.sol |  95 +++
 .../test-libraries/codec/TestLib_EIP155Tx.sol |  71 --
 .../test-libraries/codec/TestLib_OVMCodec.sol |  24 +
 .../utils/TestLib_ECDSAUtils.sol              |  33 +
 .../src/contract-deployment/config.ts         |   3 +
 .../accounts/OVM_ECDSAContractAccount.spec.ts | 140 +++-
 .../OVM_SequencerEntrypoint.spec.ts           | 128 +++-
 .../contracts/libraries/codec/Lib_EIP155Tx.ts |  15 -
 .../libraries/utils/Lib_ECDSAUtils.spec.ts    |   9 +
 packages/contracts/test/data/index.ts         |   2 +-
 .../libraries/codec/Lib_EIP155Tx.test.json    | 725 ------------------
 .../libraries/codec/Lib_OVMCodec.test.json    |  18 +
 .../libraries/utils/Lib_ECDSAUtils.test.json  | 126 +++
 .../contracts/test/helpers/codec/encoding.ts  | 116 +++
 .../helpers/test-runner/json-test-runner.ts   |  10 +-
 23 files changed, 1003 insertions(+), 1148 deletions(-)
 delete mode 100644 packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_EIP155Tx.sol
 create mode 100644 packages/contracts/contracts/optimistic-ethereum/libraries/utils/Lib_ECDSAUtils.sol
 create mode 100644 packages/contracts/contracts/optimistic-ethereum/mockOVM/accounts/mockOVM_ECDSAContractAccount.sol
 delete mode 100644 packages/contracts/contracts/test-libraries/codec/TestLib_EIP155Tx.sol
 create mode 100644 packages/contracts/contracts/test-libraries/utils/TestLib_ECDSAUtils.sol
 delete mode 100644 packages/contracts/test/contracts/libraries/codec/Lib_EIP155Tx.ts
 create mode 100644 packages/contracts/test/contracts/libraries/utils/Lib_ECDSAUtils.spec.ts
 delete mode 100644 packages/contracts/test/data/json/libraries/codec/Lib_EIP155Tx.test.json
 create mode 100644 packages/contracts/test/data/json/libraries/utils/Lib_ECDSAUtils.test.json

diff --git a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
index 10c0aa57e76f..1e13cc04b23b 100644
--- a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ECDSAContractAccount.sol
@@ -6,22 +6,21 @@ pragma experimental ABIEncoderV2;
 import { iOVM_ECDSAContractAccount } from "../../iOVM/accounts/iOVM_ECDSAContractAccount.sol";
 
 /* Library Imports */
-import { Lib_EIP155Tx } from "../../libraries/codec/Lib_EIP155Tx.sol";
+import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
+import { Lib_ECDSAUtils } from "../../libraries/utils/Lib_ECDSAUtils.sol";
 import { Lib_SafeExecutionManagerWrapper } from "../../libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol";
 import { Lib_SafeMathWrapper } from "../../libraries/wrappers/Lib_SafeMathWrapper.sol";
 
 /**
  * @title OVM_ECDSAContractAccount
  * @dev The ECDSA Contract Account can be used as the implementation for a ProxyEOA deployed by the
- * ovmCREATEEOA operation. It enables backwards compatibility with Ethereum's Layer 1, by
+ * ovmCREATEEOA operation. It enables backwards compatibility with Ethereum's Layer 1, by 
  * providing eth_sign and EIP155 formatted transaction encodings.
  *
  * Compiler used: solc
  * Runtime target: OVM
  */
 contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
-    using Lib_EIP155Tx for Lib_EIP155Tx.EIP155Tx;
-
 
     /*************
      * Constants *
@@ -39,12 +38,20 @@ contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
 
     /**
      * Executes a signed transaction.
-     * @param _encodedTransaction Signed EIP155 transaction.
+     * @param _transaction Signed EOA transaction.
+     * @param _signatureType Hashing scheme used for the transaction (e.g., ETH signed message).
+     * @param _v Signature `v` parameter.
+     * @param _r Signature `r` parameter.
+     * @param _s Signature `s` parameter.
      * @return Whether or not the call returned (rather than reverted).
      * @return Data returned by the call.
      */
     function execute(
-        bytes memory _encodedTransaction
+        bytes memory _transaction,
+        Lib_OVMCodec.EOASignatureType _signatureType,
+        uint8 _v,
+        bytes32 _r,
+        bytes32 _s
     )
         override
         public
@@ -53,29 +60,31 @@ contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
             bytes memory
         )
     {
-        Lib_EIP155Tx.EIP155Tx memory decodedTx = Lib_EIP155Tx.decode(
-            _encodedTransaction,
-            Lib_SafeExecutionManagerWrapper.safeCHAINID()
-        );
-
-        // Recovery parameter being something other than 0 or 1 indicates that this transaction was
-        // signed using the wrong chain ID. We really should have this logic inside of Lib_EIP155Tx
-        // but I'd prefer not to add the "safeREQUIRE" logic into that library. So it'll live here
-        // for now.
-        Lib_SafeExecutionManagerWrapper.safeREQUIRE(
-            decodedTx.recoveryParam < 2,
-            "OVM_ECDSAContractAccount: Transaction was signed with the wrong chain ID."
-        );
+        bool isEthSign = _signatureType == Lib_OVMCodec.EOASignatureType.ETH_SIGNED_MESSAGE;
 
         // Address of this contract within the ovm (ovmADDRESS) should be the same as the
         // recovered address of the user who signed this message. This is how we manage to shim
         // account abstraction even though the user isn't a contract.
         // Need to make sure that the transaction nonce is right and bump it if so.
         Lib_SafeExecutionManagerWrapper.safeREQUIRE(
-            decodedTx.sender() == Lib_SafeExecutionManagerWrapper.safeADDRESS(),
+            Lib_ECDSAUtils.recover(
+                _transaction,
+                isEthSign,
+                _v,
+                _r,
+                _s
+            ) == Lib_SafeExecutionManagerWrapper.safeADDRESS(),
             "Signature provided for EOA transaction execution is invalid."
         );
 
+        Lib_OVMCodec.EIP155Transaction memory decodedTx = Lib_OVMCodec.decodeEIP155Transaction(_transaction, isEthSign);
+
+        // Need to make sure that the transaction chainId is correct.
+        Lib_SafeExecutionManagerWrapper.safeREQUIRE(
+            decodedTx.chainId == Lib_SafeExecutionManagerWrapper.safeCHAINID(),
+            "Transaction chainId does not match expected OVM chainId."
+        );
+
         // Need to make sure that the transaction nonce is right.
         Lib_SafeExecutionManagerWrapper.safeREQUIRE(
             decodedTx.nonce == Lib_SafeExecutionManagerWrapper.safeGETNONCE(),
@@ -89,8 +98,7 @@ contract OVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
         //    "Gas is not sufficient to execute the transaction."
         // );
 
-        // Transfer fee to relayer. We assume that whoever called this function is the relayer,
-        // hence the usage of CALLER. Fee is computed as gasLimit * gasPrice.
+        // Transfer fee to relayer.
         address relayer = Lib_SafeExecutionManagerWrapper.safeCALLER();
         uint256 fee = Lib_SafeMathWrapper.mul(decodedTx.gasLimit, decodedTx.gasPrice);
         Lib_SafeExecutionManagerWrapper.safeREQUIRE(
diff --git a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ProxyEOA.sol b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ProxyEOA.sol
index 16127eb28ea1..0f376f821fee 100644
--- a/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ProxyEOA.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/OVM/accounts/OVM_ProxyEOA.sol
@@ -3,6 +3,8 @@ pragma solidity >0.5.0 <0.8.0;
 
 /* Library Imports */
 import { Lib_Bytes32Utils } from "../../libraries/utils/Lib_Bytes32Utils.sol";
+import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
+import { Lib_ECDSAUtils } from "../../libraries/utils/Lib_ECDSAUtils.sol";
 import { Lib_SafeExecutionManagerWrapper } from "../../libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol";
 
 /**
diff --git a/packages/contracts/contracts/optimistic-ethereum/OVM/predeploys/OVM_SequencerEntrypoint.sol b/packages/contracts/contracts/optimistic-ethereum/OVM/predeploys/OVM_SequencerEntrypoint.sol
index 0d4194c49290..bba7dd59c90f 100644
--- a/packages/contracts/contracts/optimistic-ethereum/OVM/predeploys/OVM_SequencerEntrypoint.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/OVM/predeploys/OVM_SequencerEntrypoint.sol
@@ -2,7 +2,9 @@
 pragma solidity >0.5.0 <0.8.0;
 
 /* Library Imports */
-import { Lib_EIP155Tx } from "../../libraries/codec/Lib_EIP155Tx.sol";
+import { Lib_BytesUtils } from "../../libraries/utils/Lib_BytesUtils.sol";
+import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
+import { Lib_ECDSAUtils } from "../../libraries/utils/Lib_ECDSAUtils.sol";
 import { Lib_SafeExecutionManagerWrapper } from "../../libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol";
 
 /**
@@ -17,7 +19,15 @@ import { Lib_SafeExecutionManagerWrapper } from "../../libraries/wrappers/Lib_Sa
  * Runtime target: OVM
  */
 contract OVM_SequencerEntrypoint {
-    using Lib_EIP155Tx for Lib_EIP155Tx.EIP155Tx;
+
+    /*********
+     * Enums *
+     *********/
+    
+    enum TransactionType {
+        NATIVE_ETH_TRANSACTION,
+        ETH_SIGNED_MESSAGE
+    }
 
 
     /*********************
@@ -25,47 +35,93 @@ contract OVM_SequencerEntrypoint {
      *********************/
 
     /**
-     * Expects an RLP-encoded EIP155 transaction as input. See the EIP for a more detailed
-     * description of this transaction format:
-     * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-155.md
+     * Uses a custom "compressed" format to save on calldata gas:
+     * calldata[00:01]: transaction type (0 == EIP 155, 2 == Eth Sign Message)
+     * calldata[01:33]: signature "r" parameter
+     * calldata[33:65]: signature "s" parameter
+     * calldata[65:66]: signature "v" parameter
+     * calldata[66:69]: transaction gas limit
+     * calldata[69:72]: transaction gas price
+     * calldata[72:75]: transaction nonce
+     * calldata[75:95]: transaction target address
+     * calldata[95:XX]: transaction data
      */
     fallback()
         external
     {
-        Lib_EIP155Tx.EIP155Tx memory transaction = Lib_EIP155Tx.decode(
-            msg.data,
-            Lib_SafeExecutionManagerWrapper.safeCHAINID()
-        );
+        TransactionType transactionType = _getTransactionType(Lib_BytesUtils.toUint8(msg.data, 0));
+
+        bytes32 r = Lib_BytesUtils.toBytes32(Lib_BytesUtils.slice(msg.data, 1, 32));
+        bytes32 s = Lib_BytesUtils.toBytes32(Lib_BytesUtils.slice(msg.data, 33, 32));
+        uint8 v = Lib_BytesUtils.toUint8(msg.data, 65);
+
+        // Remainder is the transaction to execute.
+        bytes memory compressedTx = Lib_BytesUtils.slice(msg.data, 66);
+        bool isEthSignedMessage = transactionType == TransactionType.ETH_SIGNED_MESSAGE;
 
-        // Recovery parameter being something other than 0 or 1 indicates that this transaction was
-        // signed using the wrong chain ID. We really should have this logic inside of the 
-        Lib_SafeExecutionManagerWrapper.safeREQUIRE(
-            transaction.recoveryParam < 2,
-            "OVM_SequencerEntrypoint: Transaction was signed with the wrong chain ID."
+        // Need to decompress and then re-encode the transaction based on the original encoding.
+        bytes memory encodedTx = Lib_OVMCodec.encodeEIP155Transaction(
+            Lib_OVMCodec.decompressEIP155Transaction(compressedTx),
+            isEthSignedMessage
         );
 
-        // Cache this result since we use it twice. Maybe we could move this caching into
-        // Lib_EIP155Tx but I'd rather not make optimizations like that right now.
-        address sender = transaction.sender();
+        address target = Lib_ECDSAUtils.recover(
+            encodedTx,
+            isEthSignedMessage,
+            uint8(v),
+            r,
+            s
+        );
 
-        // Create an EOA contract for this account if it doesn't already exist.
-        if (Lib_SafeExecutionManagerWrapper.safeEXTCODESIZE(sender) == 0) {
-            Lib_SafeExecutionManagerWrapper.safeCREATEEOA(
-                transaction.hash(),
-                transaction.recoveryParam,
-                transaction.r,
-                transaction.s
-            );
+        if (Lib_SafeExecutionManagerWrapper.safeEXTCODESIZE(target) == 0) {
+            // ProxyEOA has not yet been deployed for this EOA.
+            bytes32 messageHash = Lib_ECDSAUtils.getMessageHash(encodedTx, isEthSignedMessage);
+            Lib_SafeExecutionManagerWrapper.safeCREATEEOA(messageHash, uint8(v), r, s);
         }
 
-        // Now call into the EOA contract (which should definitely exist).
+        // ProxyEOA has been deployed for this EOA, continue to CALL.
+        bytes memory callbytes = abi.encodeWithSignature(
+            "execute(bytes,uint8,uint8,bytes32,bytes32)",
+            encodedTx,
+            isEthSignedMessage,
+            uint8(v),
+            r,
+            s
+        );
+
         Lib_SafeExecutionManagerWrapper.safeCALL(
             gasleft(),
-            sender,
-            abi.encodeWithSignature(
-                "execute(bytes)",
-                msg.data
-            )
+            target,
+            callbytes
         );
     }
+    
+
+    /**********************
+     * Internal Functions *
+     **********************/
+
+    /**
+     * Converts a uint256 into a TransactionType enum.
+     * @param _transactionType Transaction type index.
+     * @return _txType Transaction type enum value.
+     */
+    function _getTransactionType(
+        uint8 _transactionType
+    )
+        internal
+        returns (
+            TransactionType _txType
+        )
+    {
+        if (_transactionType == 0) {
+            return TransactionType.NATIVE_ETH_TRANSACTION;
+        } if (_transactionType == 2) {
+            return TransactionType.ETH_SIGNED_MESSAGE;
+        } else {
+            Lib_SafeExecutionManagerWrapper.safeREVERT(
+                "Transaction type must be 0 or 2"
+            );
+        }
+    }
 }
diff --git a/packages/contracts/contracts/optimistic-ethereum/iOVM/accounts/iOVM_ECDSAContractAccount.sol b/packages/contracts/contracts/optimistic-ethereum/iOVM/accounts/iOVM_ECDSAContractAccount.sol
index 7f3fb0f82b52..16c956580f85 100644
--- a/packages/contracts/contracts/optimistic-ethereum/iOVM/accounts/iOVM_ECDSAContractAccount.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/iOVM/accounts/iOVM_ECDSAContractAccount.sol
@@ -2,6 +2,9 @@
 pragma solidity >0.5.0 <0.8.0;
 pragma experimental ABIEncoderV2;
 
+/* Library Imports */
+import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
+
 /**
  * @title iOVM_ECDSAContractAccount
  */
@@ -12,11 +15,10 @@ interface iOVM_ECDSAContractAccount {
      ********************/
 
     function execute(
-        bytes memory _encodedTransaction
-    )
-        external
-        returns (
-            bool,
-            bytes memory
-        );
+        bytes memory _transaction,
+        Lib_OVMCodec.EOASignatureType _signatureType,
+        uint8 _v,
+        bytes32 _r,
+        bytes32 _s
+    ) external returns (bool _success, bytes memory _returndata);
 }
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_EIP155Tx.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_EIP155Tx.sol
deleted file mode 100644
index 8fa76433247b..000000000000
--- a/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_EIP155Tx.sol
+++ /dev/null
@@ -1,196 +0,0 @@
-// SPDX-License-Identifier: MIT
-pragma solidity >0.5.0 <0.8.0;
-pragma experimental ABIEncoderV2;
-
-/* Library Imports */
-import { Lib_RLPReader } from "../rlp/Lib_RLPReader.sol";
-import { Lib_RLPWriter } from "../rlp/Lib_RLPWriter.sol";
-
-/**
- * @title Lib_EIP155Tx
- * @dev A simple library for dealing with the transaction type defined by EIP155:
- *      https://github.com/ethereum/EIPs/blob/master/EIPS/eip-155.md
- */
-library Lib_EIP155Tx {
-
-    /***********
-     * Structs *
-     ***********/
-
-    // Struct representing an EIP155 transaction. See EIP link above for more information.
-    struct EIP155Tx {
-        // These fields correspond to the actual RLP-encoded fields specified by EIP155.
-        uint256 nonce;
-        uint256 gasPrice;
-        uint256 gasLimit;
-        address to;
-        uint256 value;
-        bytes data;
-        uint8 v;
-        bytes32 r;
-        bytes32 s;
-
-        // Chain ID to associate this transaction with. Used all over the place, seemed easier to
-        // set this once when we create the transaction rather than providing it as an input to
-        // each function. I don't see a strong need to have a transaction with a mutable chain ID.
-        uint256 chainId;
-
-        // The ECDSA "recovery parameter," should always be 0 or 1. EIP155 specifies that:
-        // `v = {0,1} + CHAIN_ID * 2 + 35`
-        // Where `{0,1}` is a stand in for our `recovery_parameter`. Now computing our formula for
-        // the recovery parameter:
-        // 1. `v = {0,1} + CHAIN_ID * 2 + 35`
-        // 2. `v = recovery_parameter + CHAIN_ID * 2 + 35`
-        // 3. `v - CHAIN_ID * 2 - 35 = recovery_parameter`
-        // So we're left with the final formula:
-        // `recovery_parameter = v - CHAIN_ID * 2 - 35`
-        // NOTE: This variable is a uint8 because `v` is inherently limited to a uint8. If we
-        // didn't use a uint8, then recovery_parameter would always be a negative number for chain
-        // IDs greater than 110 (`255 - 110 * 2 - 35 = 0`). So we need to wrap around to support
-        // anything larger.
-        uint8 recoveryParam; 
-
-        // Whether or not the transaction is a creation. Necessary because we can't make an address
-        // "nil". Using the zero address creates a potential conflict if the user did actually
-        // intend to send a transaction to the zero address.
-        bool isCreate;       
-    }
-
-    // Lets us use nicer syntax.
-    using Lib_EIP155Tx for EIP155Tx;
-
-
-    /**********************
-     * Internal Functions *
-     **********************/
-
-    /**
-     * Decodes an EIP155 transaction and attaches a given Chain ID.
-     * Transaction *must* be RLP-encoded.
-     * @param _encoded RLP-encoded EIP155 transaction.
-     * @param _chainId Chain ID to assocaite with this transaction.
-     * @return Parsed transaction.
-     */
-    function decode(
-        bytes memory _encoded,
-        uint256 _chainId
-    )
-        internal
-        pure
-        returns (
-            EIP155Tx memory
-        )
-    {
-        Lib_RLPReader.RLPItem[] memory decoded = Lib_RLPReader.readList(_encoded);
-
-        // Note formula above about how recoveryParam is computed.
-        uint8 v = uint8(Lib_RLPReader.readUint256(decoded[6]));
-        uint8 recoveryParam = uint8(v - 2 * _chainId - 35);
-
-        // Creations can be detected by looking at the byte length here.
-        bool isCreate = Lib_RLPReader.readBytes(decoded[3]).length == 0;
-
-        return EIP155Tx({
-            nonce: Lib_RLPReader.readUint256(decoded[0]),
-            gasPrice: Lib_RLPReader.readUint256(decoded[1]),
-            gasLimit: Lib_RLPReader.readUint256(decoded[2]),
-            to: Lib_RLPReader.readAddress(decoded[3]),
-            value: Lib_RLPReader.readUint256(decoded[4]),
-            data: Lib_RLPReader.readBytes(decoded[5]),
-            v: v,
-            r: Lib_RLPReader.readBytes32(decoded[7]),
-            s: Lib_RLPReader.readBytes32(decoded[8]),
-            chainId: _chainId,
-            recoveryParam: recoveryParam,
-            isCreate: isCreate
-        });
-    }
-
-    /**
-     * Encodes an EIP155 transaction into RLP.
-     * @param _transaction EIP155 transaction to encode.
-     * @param _includeSignature Whether or not to encode the signature.
-     * @return RLP-encoded transaction.
-     */
-    function encode(
-        EIP155Tx memory _transaction,
-        bool _includeSignature
-    )
-        internal
-        pure
-        returns (
-            bytes memory
-        )
-    {
-        bytes[] memory raw = new bytes[](9);
-
-        raw[0] = Lib_RLPWriter.writeUint(_transaction.nonce);
-        raw[1] = Lib_RLPWriter.writeUint(_transaction.gasPrice);
-        raw[2] = Lib_RLPWriter.writeUint(_transaction.gasLimit);
-
-        // We write the encoding of empty bytes when the transaction is a creation, *not* the zero
-        // address as one might assume.
-        if (_transaction.isCreate) {
-            raw[3] = Lib_RLPWriter.writeBytes('');
-        } else {
-            raw[3] = Lib_RLPWriter.writeAddress(_transaction.to);
-        }
-
-        raw[4] = Lib_RLPWriter.writeUint(_transaction.value);
-        raw[5] = Lib_RLPWriter.writeBytes(_transaction.data);
-
-        if (_includeSignature) {
-            raw[6] = Lib_RLPWriter.writeUint(_transaction.v);
-            raw[7] = Lib_RLPWriter.writeBytes32(_transaction.r);
-            raw[8] = Lib_RLPWriter.writeBytes32(_transaction.s);
-        } else {
-            // Chain ID *is* included in the unsigned transaction.
-            raw[6] = Lib_RLPWriter.writeUint(_transaction.chainId); 
-            raw[7] = Lib_RLPWriter.writeBytes('');
-            raw[8] = Lib_RLPWriter.writeBytes('');
-        }
-
-        return Lib_RLPWriter.writeList(raw);
-    }
-
-    /**
-     * Computes the hash of an EIP155 transaction. Assumes that you don't want to include the
-     * signature in this hash because that's a very uncommon usecase. If you really want to include
-     * the signature, just encode with the signature and take the hash yourself.
-     */
-    function hash(
-        EIP155Tx memory _transaction
-    )
-        internal
-        pure
-        returns (
-            bytes32
-        )
-    {
-        return keccak256(
-            _transaction.encode(false)
-        );
-    }
-
-    /**
-     * Computes the sender of an EIP155 transaction.
-     * @param _transaction EIP155 transaction to get a sender for.
-     * @return Address corresponding to the private key that signed this transaction.
-     */
-    function sender(
-        EIP155Tx memory _transaction
-    )
-        internal
-        pure
-        returns (
-            address
-        )
-    {
-        return ecrecover(
-            _transaction.hash(),
-            _transaction.recoveryParam + 27,
-            _transaction.r,
-            _transaction.s
-        );
-    }
-}
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol
index 341db0b24381..4c3c94a7424b 100644
--- a/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol
@@ -18,6 +18,11 @@ library Lib_OVMCodec {
      * Enums *
      *********/
 
+    enum EOASignatureType {
+        EIP155_TRANSACTION,
+        ETH_SIGNED_MESSAGE
+    }
+
     enum QueueOrigin {
         SEQUENCER_QUEUE,
         L1TOL2_QUEUE
@@ -81,10 +86,142 @@ library Lib_OVMCodec {
         uint40 blockNumber;
     }
 
+    struct EIP155Transaction {
+        uint256 nonce;
+        uint256 gasPrice;
+        uint256 gasLimit;
+        address to;
+        uint256 value;
+        bytes data;
+        uint256 chainId;
+    }
+
+
     /**********************
      * Internal Functions *
      **********************/
 
+    /**
+     * Decodes an EOA transaction (i.e., native Ethereum RLP encoding).
+     * @param _transaction Encoded EOA transaction.
+     * @return Transaction decoded into a struct.
+     */
+    function decodeEIP155Transaction(
+        bytes memory _transaction,
+        bool _isEthSignedMessage
+    )
+        internal
+        pure
+        returns (
+            EIP155Transaction memory
+        )
+    {
+        if (_isEthSignedMessage) {
+            (
+                uint256 _nonce,
+                uint256 _gasLimit,
+                uint256 _gasPrice,
+                uint256 _chainId,
+                address _to,
+                bytes memory _data
+            ) = abi.decode(
+                _transaction,
+                (uint256, uint256, uint256, uint256, address ,bytes)
+            );
+            return EIP155Transaction({
+                nonce: _nonce,
+                gasPrice: _gasPrice,
+                gasLimit: _gasLimit,
+                to: _to,
+                value: 0,
+                data: _data,
+                chainId: _chainId
+            });
+        } else {
+            Lib_RLPReader.RLPItem[] memory decoded = Lib_RLPReader.readList(_transaction);
+
+            return EIP155Transaction({
+                nonce: Lib_RLPReader.readUint256(decoded[0]),
+                gasPrice: Lib_RLPReader.readUint256(decoded[1]),
+                gasLimit: Lib_RLPReader.readUint256(decoded[2]),
+                to: Lib_RLPReader.readAddress(decoded[3]),
+                value: Lib_RLPReader.readUint256(decoded[4]),
+                data: Lib_RLPReader.readBytes(decoded[5]),
+                chainId:  Lib_RLPReader.readUint256(decoded[6])
+            });
+        }
+    }
+
+    /**
+     * Decompresses a compressed EIP155 transaction.
+     * @param _transaction Compressed EIP155 transaction bytes.
+     * @return Transaction parsed into a struct.
+     */
+    function decompressEIP155Transaction(
+        bytes memory _transaction
+    )
+        internal
+        returns (
+            EIP155Transaction memory
+        )
+    {
+        return EIP155Transaction({
+            gasLimit: Lib_BytesUtils.toUint24(_transaction, 0),
+            gasPrice: uint256(Lib_BytesUtils.toUint24(_transaction, 3)) * 1000000,
+            nonce: Lib_BytesUtils.toUint24(_transaction, 6),
+            to: Lib_BytesUtils.toAddress(_transaction, 9),
+            data: Lib_BytesUtils.slice(_transaction, 29),
+            chainId: Lib_SafeExecutionManagerWrapper.safeCHAINID(),
+            value: 0
+        });
+    }
+
+    /**
+     * Encodes an EOA transaction back into the original transaction.
+     * @param _transaction EIP155transaction to encode.
+     * @param _isEthSignedMessage Whether or not this was an eth signed message.
+     * @return Encoded transaction.
+     */
+    function encodeEIP155Transaction(
+        EIP155Transaction memory _transaction,
+        bool _isEthSignedMessage
+    )
+        internal
+        pure
+        returns (
+            bytes memory
+        )
+    {
+        if (_isEthSignedMessage) {
+            return abi.encode(
+                _transaction.nonce,
+                _transaction.gasLimit,
+                _transaction.gasPrice,
+                _transaction.chainId,
+                _transaction.to,
+                _transaction.data
+            );
+        } else {
+            bytes[] memory raw = new bytes[](9);
+
+            raw[0] = Lib_RLPWriter.writeUint(_transaction.nonce);
+            raw[1] = Lib_RLPWriter.writeUint(_transaction.gasPrice);
+            raw[2] = Lib_RLPWriter.writeUint(_transaction.gasLimit);
+            if (_transaction.to == address(0)) {
+                raw[3] = Lib_RLPWriter.writeBytes('');
+            } else {
+                raw[3] = Lib_RLPWriter.writeAddress(_transaction.to);
+            }
+            raw[4] = Lib_RLPWriter.writeUint(0);
+            raw[5] = Lib_RLPWriter.writeBytes(_transaction.data);
+            raw[6] = Lib_RLPWriter.writeUint(_transaction.chainId);
+            raw[7] = Lib_RLPWriter.writeBytes(bytes(''));
+            raw[8] = Lib_RLPWriter.writeBytes(bytes(''));
+
+            return Lib_RLPWriter.writeList(raw);
+        }
+    }
+
     /**
      * Encodes a standard OVM transaction.
      * @param _transaction OVM transaction to encode.
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPWriter.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPWriter.sol
index 4b9c5247bec4..8040eac0a2fa 100644
--- a/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPWriter.sol
+++ b/packages/contracts/contracts/optimistic-ethereum/libraries/rlp/Lib_RLPWriter.sol
@@ -92,23 +92,6 @@ library Lib_RLPWriter {
         return writeBytes(abi.encodePacked(_in));
     }
 
-    /**
-     * RLP encodes a bytes32 value.
-     * @param _in The bytes32 to encode.
-     * @return _out The RLP encoded bytes32 in bytes.
-     */
-    function writeBytes32(
-        bytes32 _in
-    )
-        internal
-        pure
-        returns (
-            bytes memory _out
-        )
-    {
-        return writeBytes(abi.encodePacked(_in));
-    }
-
     /**
      * RLP encodes a uint.
      * @param _in The uint256 to encode.
diff --git a/packages/contracts/contracts/optimistic-ethereum/libraries/utils/Lib_ECDSAUtils.sol b/packages/contracts/contracts/optimistic-ethereum/libraries/utils/Lib_ECDSAUtils.sol
new file mode 100644
index 000000000000..9d973758b920
--- /dev/null
+++ b/packages/contracts/contracts/optimistic-ethereum/libraries/utils/Lib_ECDSAUtils.sol
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >0.5.0 <0.8.0;
+
+/**
+ * @title Lib_ECDSAUtils
+ */
+library Lib_ECDSAUtils {
+
+    /**************************************
+     * Internal Functions: ECDSA Recovery *
+     **************************************/
+
+    /**
+     * Recovers a signed address given a message and signature.
+     * @param _message Message that was originally signed.
+     * @param _isEthSignedMessage Whether or not the user used the `Ethereum Signed Message` prefix.
+     * @param _v Signature `v` parameter.
+     * @param _r Signature `r` parameter.
+     * @param _s Signature `s` parameter.
+     * @return _sender Signer address.
+     */
+    function recover(
+        bytes memory _message,
+        bool _isEthSignedMessage,
+        uint8 _v,
+        bytes32 _r,
+        bytes32 _s
+    )
+        internal
+        pure
+        returns (
+            address _sender
+        )
+    {
+        bytes32 messageHash = getMessageHash(_message, _isEthSignedMessage);
+
+        return ecrecover(
+            messageHash,
+            _v + 27,
+            _r,
+            _s
+        );
+    }
+
+    function getMessageHash(
+        bytes memory _message,
+        bool _isEthSignedMessage
+    )
+        internal
+        pure
+        returns (bytes32) {
+        if (_isEthSignedMessage) {
+            return getEthSignedMessageHash(_message);
+        }
+        return getNativeMessageHash(_message);
+    }
+
+
+    /*************************************
+     * Private Functions: ECDSA Recovery *
+     *************************************/
+
+    /**
+     * Gets the native message hash (simple keccak256) for a message.
+     * @param _message Message to hash.
+     * @return _messageHash Native message hash.
+     */
+    function getNativeMessageHash(
+        bytes memory _message
+    )
+        private
+        pure
+        returns (
+            bytes32 _messageHash
+        )
+    {
+        return keccak256(_message);
+    }
+
+    /**
+     * Gets the hash of a message with the `Ethereum Signed Message` prefix.
+     * @param _message Message to hash.
+     * @return _messageHash Prefixed message hash.
+     */
+    function getEthSignedMessageHash(
+        bytes memory _message
+    )
+        private
+        pure
+        returns (
+            bytes32 _messageHash
+        )
+    {
+        bytes memory prefix = "\x19Ethereum Signed Message:\n32";
+        bytes32 messageHash = keccak256(_message);
+        return keccak256(abi.encodePacked(prefix, messageHash));
+    }
+}
\ No newline at end of file
diff --git a/packages/contracts/contracts/optimistic-ethereum/mockOVM/accounts/mockOVM_ECDSAContractAccount.sol b/packages/contracts/contracts/optimistic-ethereum/mockOVM/accounts/mockOVM_ECDSAContractAccount.sol
new file mode 100644
index 000000000000..15c51fcf21fb
--- /dev/null
+++ b/packages/contracts/contracts/optimistic-ethereum/mockOVM/accounts/mockOVM_ECDSAContractAccount.sol
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >0.5.0 <0.8.0;
+pragma experimental ABIEncoderV2;
+
+/* Interface Imports */
+import { iOVM_ECDSAContractAccount } from "../../iOVM/accounts/iOVM_ECDSAContractAccount.sol";
+
+/* Library Imports */
+import { Lib_OVMCodec } from "../../libraries/codec/Lib_OVMCodec.sol";
+import { Lib_ECDSAUtils } from "../../libraries/utils/Lib_ECDSAUtils.sol";
+import { Lib_SafeExecutionManagerWrapper } from "../../libraries/wrappers/Lib_SafeExecutionManagerWrapper.sol";
+
+/**
+ * @title mockOVM_ECDSAContractAccount
+ */
+contract mockOVM_ECDSAContractAccount is iOVM_ECDSAContractAccount {
+
+    /********************
+     * Public Functions *
+     ********************/
+
+    /**
+     * Executes a signed transaction.
+     * @param _transaction Signed EOA transaction.
+     * @param _signatureType Hashing scheme used for the transaction (e.g., ETH signed message).
+     * param _v Signature `v` parameter.
+     * param _r Signature `r` parameter.
+     * param _s Signature `s` parameter.
+     * @return _success Whether or not the call returned (rather than reverted).
+     * @return _returndata Data returned by the call.
+     */
+    function execute(
+        bytes memory _transaction,
+        Lib_OVMCodec.EOASignatureType _signatureType,
+        uint8, // _v,
+        bytes32, // _r,
+        bytes32 // _s
+    )
+        override
+        public
+        returns (
+            bool _success,
+            bytes memory _returndata
+        )
+    {
+        bool isEthSign = _signatureType == Lib_OVMCodec.EOASignatureType.ETH_SIGNED_MESSAGE;
+        Lib_OVMCodec.EIP155Transaction memory decodedTx = Lib_OVMCodec.decodeEIP155Transaction(_transaction, isEthSign);
+
+        // Need to make sure that the transaction nonce is right.
+        Lib_SafeExecutionManagerWrapper.safeREQUIRE(
+            decodedTx.nonce == Lib_SafeExecutionManagerWrapper.safeGETNONCE(),
+            "Transaction nonce does not match the expected nonce."
+        );
+
+        // Contract creations are signalled by sending a transaction to the zero address.
+        if (decodedTx.to == address(0)) {
+            (address created, ) = Lib_SafeExecutionManagerWrapper.safeCREATE(
+                decodedTx.gasLimit,
+                decodedTx.data
+            );
+
+            // If the created address is the ZERO_ADDRESS then we know the deployment failed, though not why
+            return (created != address(0), abi.encode(created));
+        } else {
+            // We only want to bump the nonce for `ovmCALL` because `ovmCREATE` automatically bumps
+            // the nonce of the calling account. Normally an EOA would bump the nonce for both
+            // cases, but since this is a contract we'd end up bumping the nonce twice.
+            Lib_SafeExecutionManagerWrapper.safeINCREMENTNONCE();
+
+            return Lib_SafeExecutionManagerWrapper.safeCALL(
+                decodedTx.gasLimit,
+                decodedTx.to,
+                decodedTx.data
+            );
+        }
+    }
+
+    function qall(
+        uint256 _gasLimit,
+        address _to,
+        bytes memory _data
+    )
+        public
+        returns (
+            bool _success,
+            bytes memory _returndata
+        )
+    {
+        return Lib_SafeExecutionManagerWrapper.safeCALL(
+            _gasLimit,
+            _to,
+            _data
+        );
+    }
+}
diff --git a/packages/contracts/contracts/test-libraries/codec/TestLib_EIP155Tx.sol b/packages/contracts/contracts/test-libraries/codec/TestLib_EIP155Tx.sol
deleted file mode 100644
index 6019b8695f8c..000000000000
--- a/packages/contracts/contracts/test-libraries/codec/TestLib_EIP155Tx.sol
+++ /dev/null
@@ -1,71 +0,0 @@
-// SPDX-License-Identifier: MIT
-pragma solidity >0.5.0 <0.8.0;
-pragma experimental ABIEncoderV2;
-
-/* Library Imports */
-import { Lib_EIP155Tx } from "../../optimistic-ethereum/libraries/codec/Lib_EIP155Tx.sol";
-
-/**
- * @title TestLib_EIP155Tx
- */
-contract TestLib_EIP155Tx {
-    function decode(
-        bytes memory _encoded,
-        uint256 _chainId
-    )
-        public
-        pure
-        returns (
-            Lib_EIP155Tx.EIP155Tx memory
-        )
-    {
-        return Lib_EIP155Tx.decode(
-            _encoded,
-            _chainId
-        );
-    }
-
-    function encode(
-        Lib_EIP155Tx.EIP155Tx memory _transaction,
-        bool _includeSignature
-    )
-        public
-        pure
-        returns (
-            bytes memory
-        )
-    {
-        return Lib_EIP155Tx.encode(
-            _transaction,
-            _includeSignature
-        );
-    }
-
-    function hash(
-        Lib_EIP155Tx.EIP155Tx memory _transaction
-    )
-        public
-        pure
-        returns (
-            bytes32
-        )
-    {
-        return Lib_EIP155Tx.hash(
-            _transaction
-        );
-    }
-
-    function sender(
-        Lib_EIP155Tx.EIP155Tx memory _transaction
-    )
-        public
-        pure
-        returns (
-            address
-        )
-    {
-        return Lib_EIP155Tx.sender(
-            _transaction
-        );
-    }
-}
diff --git a/packages/contracts/contracts/test-libraries/codec/TestLib_OVMCodec.sol b/packages/contracts/contracts/test-libraries/codec/TestLib_OVMCodec.sol
index 9e96dd0cd800..b9046ac8a776 100644
--- a/packages/contracts/contracts/test-libraries/codec/TestLib_OVMCodec.sol
+++ b/packages/contracts/contracts/test-libraries/codec/TestLib_OVMCodec.sol
@@ -10,6 +10,19 @@ import { Lib_OVMCodec } from "../../optimistic-ethereum/libraries/codec/Lib_OVMC
  */
 contract TestLib_OVMCodec {
 
+    function decodeEIP155Transaction(
+        bytes memory _transaction,
+        bool _isEthSignedMessage
+    )
+        public
+        pure
+        returns (
+            Lib_OVMCodec.EIP155Transaction memory _decoded
+        )
+    {
+        return Lib_OVMCodec.decodeEIP155Transaction(_transaction, _isEthSignedMessage);
+    }
+
     function encodeTransaction(
         Lib_OVMCodec.Transaction memory _transaction
     )
@@ -33,4 +46,15 @@ contract TestLib_OVMCodec {
     {
         return Lib_OVMCodec.hashTransaction(_transaction);
     }
+
+    function decompressEIP155Transaction(
+        bytes memory _transaction
+    )
+        public
+        returns (
+            Lib_OVMCodec.EIP155Transaction memory _decompressed
+        )
+    {
+        return Lib_OVMCodec.decompressEIP155Transaction(_transaction);
+    }
 }
diff --git a/packages/contracts/contracts/test-libraries/utils/TestLib_ECDSAUtils.sol b/packages/contracts/contracts/test-libraries/utils/TestLib_ECDSAUtils.sol
new file mode 100644
index 000000000000..4b66bf7f0ec8
--- /dev/null
+++ b/packages/contracts/contracts/test-libraries/utils/TestLib_ECDSAUtils.sol
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >0.5.0 <0.8.0;
+
+/* Library Imports */
+import { Lib_ECDSAUtils } from "../../optimistic-ethereum/libraries/utils/Lib_ECDSAUtils.sol";
+
+/**
+ * @title TestLib_ECDSAUtils
+ */
+contract TestLib_ECDSAUtils {
+
+    function recover(
+        bytes memory _message,
+        bool _isEthSignedMessage,
+        uint8 _v,
+        bytes32 _r,
+        bytes32 _s
+    )
+        public
+        pure
+        returns (
+            address _sender
+        )
+    {
+        return Lib_ECDSAUtils.recover(
+            _message,
+            _isEthSignedMessage,
+            _v,
+            _r,
+            _s
+        );
+    }
+}
diff --git a/packages/contracts/src/contract-deployment/config.ts b/packages/contracts/src/contract-deployment/config.ts
index 64b662ec17bf..5ddfc87b88ef 100644
--- a/packages/contracts/src/contract-deployment/config.ts
+++ b/packages/contracts/src/contract-deployment/config.ts
@@ -225,6 +225,9 @@ export const makeContractDeployConfig = async (
     OVM_ProxySequencerEntrypoint: {
       factory: getContractFactory('OVM_ProxySequencerEntrypoint'),
     },
+    mockOVM_ECDSAContractAccount: {
+      factory: getContractFactory('mockOVM_ECDSAContractAccount'),
+    },
     OVM_BondManager: {
       factory: getContractFactory('mockOVM_BondManager'),
       params: [AddressManager.address],
diff --git a/packages/contracts/test/contracts/OVM/accounts/OVM_ECDSAContractAccount.spec.ts b/packages/contracts/test/contracts/OVM/accounts/OVM_ECDSAContractAccount.spec.ts
index 0189e9c57bc1..9bb7fc5bd165 100644
--- a/packages/contracts/test/contracts/OVM/accounts/OVM_ECDSAContractAccount.spec.ts
+++ b/packages/contracts/test/contracts/OVM/accounts/OVM_ECDSAContractAccount.spec.ts
@@ -7,7 +7,14 @@ import { MockContract, smockit } from '@eth-optimism/smock'
 
 /* Internal Imports */
 import { NON_ZERO_ADDRESS } from '../../../helpers/constants'
-import { DEFAULT_EIP155_TX, decodeSolidityError } from '../../../helpers'
+import {
+  serializeNativeTransaction,
+  signNativeTransaction,
+  DEFAULT_EIP155_TX,
+  serializeEthSignTransaction,
+  signEthSignMessage,
+  decodeSolidityError,
+} from '../../../helpers'
 
 const callPredeploy = async (
   Helper_PredeployCaller: Contract,
@@ -34,9 +41,10 @@ const callPredeploy = async (
 
 describe('OVM_ECDSAContractAccount', () => {
   let wallet: Wallet
+  let badWallet: Wallet
   before(async () => {
     const provider = waffle.provider
-    ;[wallet] = provider.getWallets()
+    ;[wallet, badWallet] = provider.getWallets()
   })
 
   let Mock__OVM_ExecutionManager: MockContract
@@ -80,14 +88,43 @@ describe('OVM_ECDSAContractAccount', () => {
 
   describe('fallback()', () => {
     it(`should successfully execute an EIP155Transaction`, async () => {
-      const transaction = DEFAULT_EIP155_TX
-      const encodedTransaction = await wallet.signTransaction(transaction)
+      const message = serializeNativeTransaction(DEFAULT_EIP155_TX)
+      const sig = await signNativeTransaction(wallet, DEFAULT_EIP155_TX)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [encodedTransaction]
+        [
+          message,
+          0, // isEthSignedMessage
+          `0x${sig.v}`, //v
+          `0x${sig.r}`, //r
+          `0x${sig.s}`, //s
+        ]
+      )
+
+      // The ovmCALL is the 2nd call because the first call transfers the fee.
+      const ovmCALL: any = Mock__OVM_ExecutionManager.smocked.ovmCALL.calls[1]
+      expect(ovmCALL._address).to.equal(DEFAULT_EIP155_TX.to)
+      expect(ovmCALL._calldata).to.equal(DEFAULT_EIP155_TX.data)
+    })
+
+    it(`should successfully execute an ETHSignedTransaction`, async () => {
+      const message = serializeEthSignTransaction(DEFAULT_EIP155_TX)
+      const sig = await signEthSignMessage(wallet, DEFAULT_EIP155_TX)
+
+      await callPredeploy(
+        Helper_PredeployCaller,
+        OVM_ECDSAContractAccount,
+        'execute',
+        [
+          message,
+          1, //isEthSignedMessage
+          `0x${sig.v}`, //v
+          `0x${sig.r}`, //r
+          `0x${sig.s}`, //s
+        ]
       )
 
       // The ovmCALL is the 2nd call because the first call transfers the fee.
@@ -97,33 +134,43 @@ describe('OVM_ECDSAContractAccount', () => {
     })
 
     it(`should ovmCREATE if EIP155Transaction.to is zero address`, async () => {
-      const transaction = { ...DEFAULT_EIP155_TX, to: '' }
-      const encodedTransaction = await wallet.signTransaction(transaction)
+      const createTx = { ...DEFAULT_EIP155_TX, to: '' }
+      const message = serializeNativeTransaction(createTx)
+      const sig = await signNativeTransaction(wallet, createTx)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [encodedTransaction]
+        [
+          message,
+          0, //isEthSignedMessage
+          `0x${sig.v}`, //v
+          `0x${sig.r}`, //r
+          `0x${sig.s}`, //s
+        ]
       )
 
       const ovmCREATE: any =
         Mock__OVM_ExecutionManager.smocked.ovmCREATE.calls[0]
-      expect(ovmCREATE._bytecode).to.equal(transaction.data)
+      expect(ovmCREATE._bytecode).to.equal(createTx.data)
     })
 
     it(`should revert on invalid signature`, async () => {
-      const transaction = DEFAULT_EIP155_TX
-      const encodedTransaction = ethers.utils.serializeTransaction(
-        transaction,
-        '0x' + '00'.repeat(65)
-      )
+      const message = serializeNativeTransaction(DEFAULT_EIP155_TX)
+      const sig = await signNativeTransaction(badWallet, DEFAULT_EIP155_TX)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [encodedTransaction]
+        [
+          message,
+          0, //isEthSignedMessage
+          `0x${sig.v}`, //v
+          `0x${sig.r}`, //r
+          `0x${sig.s}`, //s
+        ]
       )
       const ovmREVERT: any =
         Mock__OVM_ExecutionManager.smocked.ovmREVERT.calls[0]
@@ -133,14 +180,24 @@ describe('OVM_ECDSAContractAccount', () => {
     })
 
     it(`should revert on incorrect nonce`, async () => {
-      const transaction = { ...DEFAULT_EIP155_TX, nonce: 99 }
-      const encodedTransaction = await wallet.signTransaction(transaction)
+      const alteredNonceTx = {
+        ...DEFAULT_EIP155_TX,
+        nonce: 99,
+      }
+      const message = serializeNativeTransaction(alteredNonceTx)
+      const sig = await signNativeTransaction(wallet, alteredNonceTx)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [encodedTransaction]
+        [
+          message,
+          0, //isEthSignedMessage
+          `0x${sig.v}`, //v
+          `0x${sig.r}`, //r
+          `0x${sig.s}`, //s
+        ]
       )
       const ovmREVERT: any =
         Mock__OVM_ExecutionManager.smocked.ovmREVERT.calls[0]
@@ -150,32 +207,52 @@ describe('OVM_ECDSAContractAccount', () => {
     })
 
     it(`should revert on incorrect chainId`, async () => {
-      const transaction = { ...DEFAULT_EIP155_TX, chainId: 421 }
-      const encodedTransaction = await wallet.signTransaction(transaction)
+      const alteredChainIdTx = {
+        ...DEFAULT_EIP155_TX,
+        chainId: 421,
+      }
+      const message = serializeNativeTransaction(alteredChainIdTx)
+      const sig = await signNativeTransaction(wallet, alteredChainIdTx)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [encodedTransaction]
+        [
+          message,
+          0, //isEthSignedMessage
+          `0x${sig.v}`, //v
+          `0x${sig.r}`, //r
+          `0x${sig.s}`, //s
+        ]
       )
       const ovmREVERT: any =
         Mock__OVM_ExecutionManager.smocked.ovmREVERT.calls[0]
       expect(decodeSolidityError(ovmREVERT._data)).to.equal(
-        'OVM_ECDSAContractAccount: Transaction was signed with the wrong chain ID.'
+        'Transaction chainId does not match expected OVM chainId.'
       )
     })
 
     // TEMPORARY: Skip gas checks for minnet.
     it.skip(`should revert on insufficient gas`, async () => {
-      const transaction = { ...DEFAULT_EIP155_TX, gasLimit: 200000000 }
-      const encodedTransaction = await wallet.signTransaction(transaction)
+      const alteredInsufficientGasTx = {
+        ...DEFAULT_EIP155_TX,
+        gasLimit: 200000000,
+      }
+      const message = serializeNativeTransaction(alteredInsufficientGasTx)
+      const sig = await signNativeTransaction(wallet, alteredInsufficientGasTx)
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [encodedTransaction],
+        [
+          message,
+          0, //isEthSignedMessage
+          `0x${sig.v}`, //v
+          `0x${sig.r}`, //r
+          `0x${sig.s}`, //s
+        ],
         40000000
       )
 
@@ -187,16 +264,21 @@ describe('OVM_ECDSAContractAccount', () => {
     })
 
     it(`should revert if fee is not transferred to the relayer`, async () => {
-      const transaction = DEFAULT_EIP155_TX
-      const encodedTransaction = await wallet.signTransaction(transaction)
-
+      const message = serializeNativeTransaction(DEFAULT_EIP155_TX)
+      const sig = await signNativeTransaction(wallet, DEFAULT_EIP155_TX)
       Mock__OVM_ExecutionManager.smocked.ovmCALL.will.return.with([false, '0x'])
 
       await callPredeploy(
         Helper_PredeployCaller,
         OVM_ECDSAContractAccount,
         'execute',
-        [encodedTransaction],
+        [
+          message,
+          0, //isEthSignedMessage
+          `0x${sig.v}`, //v
+          `0x${sig.r}`, //r
+          `0x${sig.s}`, //s
+        ],
         40000000
       )
 
diff --git a/packages/contracts/test/contracts/OVM/precompiles/OVM_SequencerEntrypoint.spec.ts b/packages/contracts/test/contracts/OVM/precompiles/OVM_SequencerEntrypoint.spec.ts
index 81bd75986c94..2979ad3bc33e 100644
--- a/packages/contracts/test/contracts/OVM/precompiles/OVM_SequencerEntrypoint.spec.ts
+++ b/packages/contracts/test/contracts/OVM/precompiles/OVM_SequencerEntrypoint.spec.ts
@@ -7,7 +7,14 @@ import { smockit, MockContract } from '@eth-optimism/smock'
 
 /* Internal Imports */
 import { getContractInterface } from '../../../../src'
-import { DEFAULT_EIP155_TX } from '../../../helpers'
+import {
+  encodeSequencerCalldata,
+  signNativeTransaction,
+  signEthSignMessage,
+  DEFAULT_EIP155_TX,
+  serializeNativeTransaction,
+  serializeEthSignTransaction,
+} from '../../../helpers'
 
 describe('OVM_SequencerEntrypoint', () => {
   let wallet: Wallet
@@ -48,59 +55,128 @@ describe('OVM_SequencerEntrypoint', () => {
   })
 
   describe('fallback()', async () => {
-    it('should call EIP155', async () => {
-      const transaction = DEFAULT_EIP155_TX
-      const encodedTransaction = await wallet.signTransaction(transaction)
-
+    it('should call EIP155 if the transaction type is 0', async () => {
+      const calldata = await encodeSequencerCalldata(
+        wallet,
+        DEFAULT_EIP155_TX,
+        0
+      )
       await Helper_PredeployCaller.callPredeploy(
         OVM_SequencerEntrypoint.address,
-        encodedTransaction
+        calldata
       )
 
+      const encodedTx = serializeNativeTransaction(DEFAULT_EIP155_TX)
+      const sig = await signNativeTransaction(wallet, DEFAULT_EIP155_TX)
+
       const expectedEOACalldata = getContractInterface(
         'OVM_ECDSAContractAccount'
-      ).encodeFunctionData('execute', [encodedTransaction])
+      ).encodeFunctionData('execute', [
+        encodedTx,
+        0, //isEthSignedMessage
+        `0x${sig.v}`, //v
+        `0x${sig.r}`, //r
+        `0x${sig.s}`, //s
+      ])
       const ovmCALL: any = Mock__OVM_ExecutionManager.smocked.ovmCALL.calls[0]
       expect(ovmCALL._address).to.equal(await wallet.getAddress())
       expect(ovmCALL._calldata).to.equal(expectedEOACalldata)
     })
 
-    it('should send correct calldata if tx is a create', async () => {
-      const transaction = { ...DEFAULT_EIP155_TX, to: '' }
-      const encodedTransaction = await wallet.signTransaction(transaction)
-
+    it('should send correct calldata if tx is a create and the transaction type is 0', async () => {
+      const createTx = { ...DEFAULT_EIP155_TX, to: '' }
+      const calldata = await encodeSequencerCalldata(wallet, createTx, 0)
       await Helper_PredeployCaller.callPredeploy(
         OVM_SequencerEntrypoint.address,
-        encodedTransaction
+        calldata
       )
 
+      const encodedTx = serializeNativeTransaction(createTx)
+      const sig = await signNativeTransaction(wallet, createTx)
+
       const expectedEOACalldata = getContractInterface(
         'OVM_ECDSAContractAccount'
-      ).encodeFunctionData('execute', [encodedTransaction])
+      ).encodeFunctionData('execute', [
+        encodedTx,
+        0, //isEthSignedMessage
+        `0x${sig.v}`, //v
+        `0x${sig.r}`, //r
+        `0x${sig.s}`, //s
+      ])
       const ovmCALL: any = Mock__OVM_ExecutionManager.smocked.ovmCALL.calls[0]
       expect(ovmCALL._address).to.equal(await wallet.getAddress())
       expect(ovmCALL._calldata).to.equal(expectedEOACalldata)
     })
 
-    it(`should call ovmCreateEOA when ovmEXTCODESIZE returns 0`, async () => {
-      Mock__OVM_ExecutionManager.smocked.ovmEXTCODESIZE.will.return.with(0)
-
-      const transaction = DEFAULT_EIP155_TX
-      const encodedTransaction = await wallet.signTransaction(transaction)
+    for (let i = 0; i < 3; i += 2) {
+      it(`should call ovmCreateEOA when tx type is ${i} and ovmEXTCODESIZE returns 0`, async () => {
+        Mock__OVM_ExecutionManager.smocked.ovmEXTCODESIZE.will.return.with(0)
+        const calldata = await encodeSequencerCalldata(
+          wallet,
+          DEFAULT_EIP155_TX,
+          i
+        )
+        await Helper_PredeployCaller.callPredeploy(
+          OVM_SequencerEntrypoint.address,
+          calldata
+        )
+        const call: any =
+          Mock__OVM_ExecutionManager.smocked.ovmCREATEEOA.calls[0]
+        const eoaAddress = ethers.utils.recoverAddress(call._messageHash, {
+          v: call._v + 27,
+          r: call._r,
+          s: call._s,
+        })
+        expect(eoaAddress).to.equal(await wallet.getAddress())
+      })
+    }
 
+    it('should submit ETHSignedTypedData if TransactionType is 2', async () => {
+      const calldata = await encodeSequencerCalldata(
+        wallet,
+        DEFAULT_EIP155_TX,
+        2
+      )
       await Helper_PredeployCaller.callPredeploy(
         OVM_SequencerEntrypoint.address,
-        encodedTransaction
+        calldata
       )
 
-      const call: any = Mock__OVM_ExecutionManager.smocked.ovmCREATEEOA.calls[0]
-      const eoaAddress = ethers.utils.recoverAddress(call._messageHash, {
-        v: call._v + 27,
-        r: call._r,
-        s: call._s,
-      })
+      const encodedTx = serializeEthSignTransaction(DEFAULT_EIP155_TX)
+      const sig = await signEthSignMessage(wallet, DEFAULT_EIP155_TX)
+
+      const expectedEOACalldata = getContractInterface(
+        'OVM_ECDSAContractAccount'
+      ).encodeFunctionData('execute', [
+        encodedTx,
+        1, //isEthSignedMessage
+        `0x${sig.v}`, //v
+        `0x${sig.r}`, //r
+        `0x${sig.s}`, //s
+      ])
+      const ovmCALL: any = Mock__OVM_ExecutionManager.smocked.ovmCALL.calls[0]
+      expect(ovmCALL._address).to.equal(await wallet.getAddress())
+      expect(ovmCALL._calldata).to.equal(expectedEOACalldata)
+    })
+
+    it('should revert if TransactionType is >2', async () => {
+      const calldata = '0x03'
+      await expect(
+        Helper_PredeployCaller.callPredeploy(
+          OVM_SequencerEntrypoint.address,
+          calldata
+        )
+      ).to.be.reverted
+    })
 
-      expect(eoaAddress).to.equal(await wallet.getAddress())
+    it('should revert if TransactionType is 1', async () => {
+      const calldata = '0x01'
+      await expect(
+        Helper_PredeployCaller.callPredeploy(
+          OVM_SequencerEntrypoint.address,
+          calldata
+        )
+      ).to.be.reverted
     })
   })
 })
diff --git a/packages/contracts/test/contracts/libraries/codec/Lib_EIP155Tx.ts b/packages/contracts/test/contracts/libraries/codec/Lib_EIP155Tx.ts
deleted file mode 100644
index 021f14edcb19..000000000000
--- a/packages/contracts/test/contracts/libraries/codec/Lib_EIP155Tx.ts
+++ /dev/null
@@ -1,15 +0,0 @@
-/* tslint:disable:no-empty */
-import '../../../setup'
-
-/* Internal Imports */
-import { Lib_EIP155Tx_TEST_JSON } from '../../../data'
-import { runJsonTest } from '../../../helpers'
-
-// Currently running tests from here:
-// https://github.com/ethereumjs/ethereumjs-tx/blob/master/test/ttTransactionTestEip155VitaliksTests.json
-
-describe('Lib_EIP155Tx', () => {
-  describe('JSON tests', () => {
-    runJsonTest('TestLib_EIP155Tx', Lib_EIP155Tx_TEST_JSON)
-  })
-})
diff --git a/packages/contracts/test/contracts/libraries/utils/Lib_ECDSAUtils.spec.ts b/packages/contracts/test/contracts/libraries/utils/Lib_ECDSAUtils.spec.ts
new file mode 100644
index 000000000000..baf3c5a999b2
--- /dev/null
+++ b/packages/contracts/test/contracts/libraries/utils/Lib_ECDSAUtils.spec.ts
@@ -0,0 +1,9 @@
+/* Internal Imports */
+import { Lib_ECDSAUtils_TEST_JSON } from '../../../data'
+import { runJsonTest } from '../../../helpers'
+
+describe('Lib_ECDSAUtils', () => {
+  describe('JSON tests', () => {
+    runJsonTest('TestLib_ECDSAUtils', Lib_ECDSAUtils_TEST_JSON)
+  })
+})
diff --git a/packages/contracts/test/data/index.ts b/packages/contracts/test/data/index.ts
index 5c9103f5c2d5..8a4a1f7e65b8 100644
--- a/packages/contracts/test/data/index.ts
+++ b/packages/contracts/test/data/index.ts
@@ -2,8 +2,8 @@ export { tests as Lib_RLPWriter_TEST_JSON } from './json/libraries/rlp/Lib_RLPWr
 export { tests as Lib_RLPReader_TEST_JSON } from './json/libraries/rlp/Lib_RLPReader.test.json'
 export { tests as Lib_Bytes32Utils_TEST_JSON } from './json/libraries/utils/Lib_Bytes32Utils.test.json'
 export { tests as Lib_BytesUtils_TEST_JSON } from './json/libraries/utils/Lib_BytesUtils.test.json'
+export { tests as Lib_ECDSAUtils_TEST_JSON } from './json/libraries/utils/Lib_ECDSAUtils.test.json'
 export { tests as Lib_MerkleTrie_TEST_JSON } from './json/libraries/trie/Lib_MerkleTrie.test.json'
-export { tests as Lib_EIP155Tx_TEST_JSON } from './json/libraries/codec/Lib_EIP155Tx.test.json'
 export { tests as Lib_OVMCodec_TEST_JSON } from './json/libraries/codec/Lib_OVMCodec.test.json'
 export { tests as CREATE2_TEST_JSON } from './json/create2.test.json'
 export { tests as SAFETY_CHECKER_TEST_JSON } from './json/safety-checker.test.json'
diff --git a/packages/contracts/test/data/json/libraries/codec/Lib_EIP155Tx.test.json b/packages/contracts/test/data/json/libraries/codec/Lib_EIP155Tx.test.json
deleted file mode 100644
index a7536ad4fa3b..000000000000
--- a/packages/contracts/test/data/json/libraries/codec/Lib_EIP155Tx.test.json
+++ /dev/null
@@ -1,725 +0,0 @@
-{
-    "tests": {
-        "decode": {
-            "vitalik test 0": {
-                "in": [
-                    "0xf864808504a817c800825208943535353535353535353535353535353535353535808025a0044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116da0044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
-                    1
-                ],
-                "out": [
-                    [
-                        "0x00",
-                        "0x04a817c800",
-                        "0x5208",
-                        "0x3535353535353535353535353535353535353535",
-                        "0x00",
-                        "0x",
-                        "0x25",
-                        "0x044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
-                        "0x044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
-                        "0x01",
-                        "0x00",
-                        false
-                    ]
-                ]
-            },
-            "vitalik test 1": {
-                "in": [
-                    "0xf867088504a817c8088302e2489435353535353535353535353535353535353535358202008025a064b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c12a064b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c10",
-                    1
-                ],
-                "out": [
-                    [
-                        "0x08",
-                        "0x04a817c808",
-                        "0x02e248",
-                        "0x3535353535353535353535353535353535353535",
-                        "0x0200",
-                        "0x",
-                        "0x25",
-                        "0x64b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c12",
-                        "0x64b1702d9298fee62dfeccc57d322a463ad55ca201256d01f62b45b2e1c21c10",
-                        "0x01",
-                        "0x00",
-                        false
-                    ]
-                ]
-            },
-            "vitalik test 2": {
-                "in": [
-                    "0xf867098504a817c809830334509435353535353535353535353535353535353535358202d98025a052f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afba052f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb",
-                    1
-                ],
-                "out": [
-                    [
-                        "0x09",
-                        "0x04a817c809",
-                        "0x033450",
-                        "0x3535353535353535353535353535353535353535",
-                        "0x02d9",
-                        "0x",
-                        "0x25",
-                        "0x52f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb",
-                        "0x52f8f61201b2b11a78d6e866abc9c3db2ae8631fa656bfe5cb53668255367afb",
-                        "0x01",
-                        "0x00",
-                        false
-                    ]
-                ]
-            },
-            "vitalik test 3": {
-                "in": [
-                    "0xf864018504a817c80182a410943535353535353535353535353535353535353535018025a0489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bcaa0489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bc6",
-                    1
-                ],
-                "out": [
-                    [
-                        "0x01",
-                        "0x04a817c801",
-                        "0xa410",
-                        "0x3535353535353535353535353535353535353535",
-                        "0x01",
-                        "0x",
-                        "0x25",
-                        "0x489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bca",
-                        "0x489efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bc6",
-                        "0x01",
-                        "0x00",
-                        false
-                    ]
-                ]
-            },
-            "vitalik test 4": {
-                "in": [
-                    "0xf864028504a817c80282f618943535353535353535353535353535353535353535088025a02d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5a02d7c5bef027816a800da1736444fb58a807ef4c9603b7848673f7e3a68eb14a5",
-                    1
-                ],
-                "out": [
-                    [
-                        "0x02",
-                        "0x04a817c802",
-                        "0xf618",
-                        "0x3535353535353535353535353535353535353535",
-                        "0x08",
-                        "0x",
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-            },
-            "vitalik test 5": {
-                "in": [
-                    [
-                        "0x03",
-                        "0x04a817c803",
-                        "0x014820",
-                        "0x3535353535353535353535353535353535353535",
-                        "0x1b",
-                        "0x",
-                        "0x25",
-                        "0x2a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4e0",
-                        "0x2a80e1ef1d7842f27f2e6be0972bb708b9a135c38860dbe73c27c3486c34f4de",
-                        "0x01",
-                        "0x00",
-                        false
-                    ]
-                ],
-                "out": [
-                    "0x82a88539669a3fd524d669e858935de5e5410cf0"
-                ]
-            },
-            "vitalik test 6": {
-                "in": [
-                    [
-                        "0x04",
-                        "0x04a817c804",
-                        "0x019a28",
-                        "0x3535353535353535353535353535353535353535",
-                        "0x40",
-                        "0x",
-                        "0x25",
-                        "0x13600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c063",
-                        "0x13600b294191fc92924bb3ce4b969c1e7e2bab8f4c93c3fc6d0a51733df3c060",
-                        "0x01",
-                        "0x00",
-                        false
-                    ]
-                ],
-                "out": [
-                    "0xf9358f2538fd5ccfeb848b64a96b743fcc930554"
-                ]
-            },
-            "vitalik test 7": {
-                "in": [
-                    [
-                        "0x05",
-                        "0x04a817c805",
-                        "0x01ec30",
-                        "0x3535353535353535353535353535353535353535",
-                        "0x7d",
-                        "0x",
-                        "0x25",
-                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
-                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
-                        "0x01",
-                        "0x00",
-                        false
-                    ]
-                ],
-                "out": [
-                    "0xa8f7aba377317440bc5b26198a363ad22af1f3a4"
-                ]
-            },
-            "vitalik test 8": {
-                "in": [
-                    [
-                        "0x05",
-                        "0x04a817c805",
-                        "0x01ec30",
-                        "0x3535353535353535353535353535353535353535",
-                        "0x7d",
-                        "0x",
-                        "0x25",
-                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
-                        "0x4eebf77a833b30520287ddd9478ff51abbdffa30aa90a8d655dba0e8a79ce0c1",
-                        "0x01",
-                        "0x00",
-                        false
-                    ]
-                ],
-                "out": [
-                    "0xa8f7aba377317440bc5b26198a363ad22af1f3a4"
-                ]
-            },
-            "vitalik test 9": {
-                "in": [
-                    [
-                        "0x06",
-                        "0x04a817c806",
-                        "0x023e38",
-                        "0x3535353535353535353535353535353535353535",
-                        "0xd8",
-                        "0x",
-                        "0x25",
-                        "0x6455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2f",
-                        "0x6455bf8ea6e7463a1046a0b52804526e119b4bf5136279614e0b1e8e296a4e2d",
-                        "0x01",
-                        "0x00",
-                        false
-                    ]
-                ],
-                "out": [
-                    "0xf1f571dc362a0e5b2696b8e775f8491d3e50de35"
-                ]
-            },
-            "vitalik test 10": {
-                "in": [
-                    [
-                        "0x07",
-                        "0x04a817c807",
-                        "0x029040",
-                        "0x3535353535353535353535353535353535353535",
-                        "0x0157",
-                        "0x",
-                        "0x25",
-                        "0x52f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021",
-                        "0x52f1a9b320cab38e5da8a8f97989383aab0a49165fc91c737310e4f7e9821021",
-                        "0x01",
-                        "0x00",
-                        false
-                    ]
-                ],
-                "out": [
-                    "0xd37922162ab7cea97c97a87551ed02c9a38b7332"
-                ]
-            }
-        }
-    }
-}
diff --git a/packages/contracts/test/data/json/libraries/codec/Lib_OVMCodec.test.json b/packages/contracts/test/data/json/libraries/codec/Lib_OVMCodec.test.json
index a55ce0122c21..b442f4e07c8c 100644
--- a/packages/contracts/test/data/json/libraries/codec/Lib_OVMCodec.test.json
+++ b/packages/contracts/test/data/json/libraries/codec/Lib_OVMCodec.test.json
@@ -1,4 +1,22 @@
 {
     "tests": {
+        "decompressEIP155Transaction": {
+            "decompression": {
+                "in": [
+                    "0x0001f4000064000064121212121212121212121212121212121212121299999999999999999999"
+                ],
+                "out": [
+                    [
+                        100,
+                        100000000,
+                        500,
+                        "0x1212121212121212121212121212121212121212",
+                        0,
+                        "0x99999999999999999999",
+                        420
+                    ]
+                ]
+            }
+        }
     }
 }
diff --git a/packages/contracts/test/data/json/libraries/utils/Lib_ECDSAUtils.test.json b/packages/contracts/test/data/json/libraries/utils/Lib_ECDSAUtils.test.json
new file mode 100644
index 000000000000..40f15819442f
--- /dev/null
+++ b/packages/contracts/test/data/json/libraries/utils/Lib_ECDSAUtils.test.json
@@ -0,0 +1,126 @@
+{
+    "tests": {
+        "recover": {
+            "standard hash, valid signature": {
+                "in": [
+                    "0xf83d80808094121212121212121212121212121212121212121280a0bc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a6c8080",
+                    false,
+                    "0x01",
+                    "0x057bf1c0edf0a9002a79f8c9b39683f6453a18e73e02364270a2b6ee8117f11a",
+                    "0x5f8181365a222c7b05a84c29a29754e6a925952d3bf4bd65a6259ef37ee048e3"
+                ],
+                "out": [
+                    "0x17ec8597ff92C3F44523bDc65BF0f1bE632917ff"
+                ]
+            },
+            "standard hash, invalid v parameter": {
+                "in": [
+                    "0xf83d80808094121212121212121212121212121212121212121280a0bc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a6c8080",
+                    false,
+                    "0xfc",
+                    "0x057bf1c0edf0a9002a79f8c9b39683f6453a18e73e02364270a2b6ee8117f11a",
+                    "0x5f8181365a222c7b05a84c29a29754e6a925952d3bf4bd65a6259ef37ee048e3"
+                ],
+                "out": [
+                    "0x0000000000000000000000000000000000000000"
+                ]
+            },
+            "standard hash, invalid r parameter": {
+                "in": [
+                    "0xf83d80808094121212121212121212121212121212121212121280a0bc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a6c8080",
+                    false,
+                    "0x01",
+                    "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    "0x5f8181365a222c7b05a84c29a29754e6a925952d3bf4bd65a6259ef37ee048e3"
+                ],
+                "out": [
+                    "0x0000000000000000000000000000000000000000"
+                ]
+            },
+            "standard hash, invalid s parameter": {
+                "in": [
+                    "0xf83d80808094121212121212121212121212121212121212121280a0bc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a6c8080",
+                    false,
+                    "0x01",
+                    "0x057bf1c0edf0a9002a79f8c9b39683f6453a18e73e02364270a2b6ee8117f11a",
+                    "0x0000000000000000000000000000000000000000000000000000000000000000"
+                ],
+                "out": [
+                    "0x0000000000000000000000000000000000000000"
+                ]
+            },
+            "standard hash, invalid message": {
+                "in": [
+                    "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    false,
+                    "0x01",
+                    "0x057bf1c0edf0a9002a79f8c9b39683f6453a18e73e02364270a2b6ee8117f11a",
+                    "0x5f8181365a222c7b05a84c29a29754e6a925952d3bf4bd65a6259ef37ee048e3"
+                ],
+                "out": [
+                    "0x1397890fcfC2D7563Aa01cE93A217b9809D3447B"
+                ]
+            },
+            "eth signed message hash, valid signature": {
+                "in": [
+                    "0x000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006c000000000000000000000000121212121212121212121212121212121212121200000000000000000000000000000000000000000000000000000000000000c00000000000000000000000000000000000000000000000000000000000000020bc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a",
+                    true,
+                    "0x01",
+                    "0xe5a2edb71b6d76a8aacd59467d3063fd455ca13a4e9cb57da6f25849d40e4e2a",
+                    "0x5465373d68d521845e3ffd2baf4c51f3d21c990914c09490b32ffc0b322dbf98"
+                ],
+                "out": [
+                    "0x17ec8597ff92C3F44523bDc65BF0f1bE632917ff"
+                ]
+            },
+            "eth signed message hash, invalid v parameter": {
+                "in": [
+                    "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",
+                    true,
+                    "0x1c",
+                    "0xe5a2edb71b6d76a8aacd59467d3063fd455ca13a4e9cb57da6f25849d40e4e2a",
+                    "0x5465373d68d521845e3ffd2baf4c51f3d21c990914c09490b32ffc0b322dbf98"
+                ],
+                "out": [
+                    "0x0000000000000000000000000000000000000000"
+                ]
+            },
+            "eth signed message hash, invalid r parameter": {
+                "in": [
+                    "0x000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006c000000000000000000000000121212121212121212121212121212121212121200000000000000000000000000000000000000000000000000000000000000c00000000000000000000000000000000000000000000000000000000000000020bc36789e7a1e281436464229828f817d6612f7b477d66591ff96a9e064bcc98a",
+                    true,
+                    "0x01",
+                    "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    "0x5465373d68d521845e3ffd2baf4c51f3d21c990914c09490b32ffc0b322dbf98"
+                ],
+                "out": [
+                    "0x0000000000000000000000000000000000000000"
+                ]
+            },
+            "eth signed message hash, invalid s parameter": {
+                "in": [
+                    "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",
+                    true,
+                    "0x01",
+                    "0xe5a2edb71b6d76a8aacd59467d3063fd455ca13a4e9cb57da6f25849d40e4e2a",
+                    "0x0000000000000000000000000000000000000000000000000000000000000000"
+                ],
+                "out": [
+                    "0x0000000000000000000000000000000000000000"
+                ]
+            },
+            "eth signed message hash, invalid message": {
+                "in": [
+                    "0x0000000000000000000000000000000000000000000000000000000000000000",
+                    true,
+                    "0x01",
+                    "0xe5a2edb71b6d76a8aacd59467d3063fd455ca13a4e9cb57da6f25849d40e4e2a",
+                    "0x5465373d68d521845e3ffd2baf4c51f3d21c990914c09490b32ffc0b322dbf98"
+                ],
+                "out": [
+                    "0xf8bd1421f9D28C8F58f33B25a6faB16F3f89b749"
+                ]
+            }
+        }
+    }
+}
diff --git a/packages/contracts/test/helpers/codec/encoding.ts b/packages/contracts/test/helpers/codec/encoding.ts
index 869e4feffca0..f7e16531fcd6 100644
--- a/packages/contracts/test/helpers/codec/encoding.ts
+++ b/packages/contracts/test/helpers/codec/encoding.ts
@@ -1,5 +1,9 @@
 /* External Imports */
 import { ethers } from 'hardhat'
+import { constants, Wallet } from 'ethers'
+
+/* Internal Imports */
+import { remove0x, fromHexString } from '@eth-optimism/core-utils'
 
 export interface EIP155Transaction {
   nonce: number
@@ -33,3 +37,115 @@ export const getRawSignedComponents = (signed: string): any[] => {
 export const getSignedComponents = (signed: string): any[] => {
   return ethers.utils.RLP.decode(signed).slice(-3)
 }
+
+export const encodeCompactTransaction = (transaction: any): string => {
+  const nonce = ethers.utils.zeroPad(transaction.nonce, 3)
+  const gasLimit = ethers.utils.zeroPad(transaction.gasLimit, 3)
+  if (transaction.gasPrice % 1000000 !== 0)
+    throw Error('gas price must be a multiple of 1000000')
+  const compressedGasPrice: any = transaction.gasPrice / 1000000
+  const gasPrice = ethers.utils.zeroPad(compressedGasPrice, 3)
+  const to = !transaction.to.length
+    ? fromHexString(constants.AddressZero)
+    : fromHexString(transaction.to)
+  const data = fromHexString(transaction.data)
+
+  return Buffer.concat([
+    Buffer.from(gasLimit),
+    Buffer.from(gasPrice),
+    Buffer.from(nonce),
+    Buffer.from(to),
+    data,
+  ]).toString('hex')
+}
+
+export const serializeEthSignTransaction = (
+  transaction: EIP155Transaction
+): string => {
+  return ethers.utils.defaultAbiCoder.encode(
+    ['uint256', 'uint256', 'uint256', 'uint256', 'address', 'bytes'],
+    [
+      transaction.nonce,
+      transaction.gasLimit,
+      transaction.gasPrice,
+      transaction.chainId,
+      transaction.to,
+      transaction.data,
+    ]
+  )
+}
+
+export const serializeNativeTransaction = (
+  transaction: EIP155Transaction
+): string => {
+  return ethers.utils.serializeTransaction(transaction)
+}
+
+export const signEthSignMessage = async (
+  wallet: Wallet,
+  transaction: EIP155Transaction
+): Promise<SignatureParameters> => {
+  const serializedTransaction = serializeEthSignTransaction(transaction)
+  const transactionHash = ethers.utils.keccak256(serializedTransaction)
+  const transactionHashBytes = ethers.utils.arrayify(transactionHash)
+  const transactionSignature = await wallet.signMessage(transactionHashBytes)
+
+  const messageHash = ethers.utils.hashMessage(transactionHashBytes)
+  const [v, r, s] = getRawSignedComponents(transactionSignature).map(
+    (component) => {
+      return remove0x(component)
+    }
+  )
+  return {
+    messageHash,
+    v: '0' + (parseInt(v, 16) - 27),
+    r,
+    s,
+  }
+}
+
+export const signNativeTransaction = async (
+  wallet: Wallet,
+  transaction: EIP155Transaction
+): Promise<SignatureParameters> => {
+  const serializedTransaction = serializeNativeTransaction(transaction)
+  const transactionSignature = await wallet.signTransaction(transaction)
+
+  const messageHash = ethers.utils.keccak256(serializedTransaction)
+  const [v, r, s] = getSignedComponents(transactionSignature).map(
+    (component) => {
+      return remove0x(component)
+    }
+  )
+  return {
+    messageHash,
+    v: '0' + (parseInt(v, 16) - transaction.chainId * 2 - 8 - 27),
+    r,
+    s,
+  }
+}
+
+export const signTransaction = async (
+  wallet: Wallet,
+  transaction: EIP155Transaction,
+  transactionType: number
+): Promise<SignatureParameters> => {
+  return transactionType === 2
+    ? signEthSignMessage(wallet, transaction) //ETH Signed tx
+    : signNativeTransaction(wallet, transaction) //Create EOA tx or EIP155 tx
+}
+
+export const encodeSequencerCalldata = async (
+  wallet: Wallet,
+  transaction: EIP155Transaction,
+  transactionType: number
+) => {
+  const sig = await signTransaction(wallet, transaction, transactionType)
+  const encodedTransaction = encodeCompactTransaction(transaction)
+  const dataPrefix = `0x0${transactionType}${sig.r}${sig.s}${sig.v}`
+  const calldata =
+    transactionType === 1
+      ? `${dataPrefix}${remove0x(sig.messageHash)}` // Create EOA tx
+      : `${dataPrefix}${encodedTransaction}` // EIP155 tx or ETH Signed Tx
+  return calldata
+}
diff --git a/packages/contracts/test/helpers/test-runner/json-test-runner.ts b/packages/contracts/test/helpers/test-runner/json-test-runner.ts
index d32626835f5f..0380ee849f06 100644
--- a/packages/contracts/test/helpers/test-runner/json-test-runner.ts
+++ b/packages/contracts/test/helpers/test-runner/json-test-runner.ts
@@ -4,16 +4,10 @@ import { expect } from '../../setup'
 import { ethers } from 'hardhat'
 import { Contract, BigNumber } from 'ethers'
 
-const bnRegex = /^\d+n$/gm
-
-const bigNumberify = (arr: any[]) => {
+const bigNumberify = (arr) => {
   return arr.map((el: any) => {
     if (typeof el === 'number') {
       return BigNumber.from(el)
-    } else if (typeof el === 'string' && bnRegex.test(el)) {
-      return BigNumber.from(el.slice(0, el.length - 1))
-    } else if (typeof el === 'string' && el.length > 2 && el.startsWith('0x')) {
-      return BigNumber.from(el.toLowerCase())
     } else if (Array.isArray(el)) {
       return bigNumberify(el)
     } else {
@@ -37,7 +31,7 @@ export const runJsonTest = (contractName: string, json: any): void => {
               .reverted
           } else {
             expect(
-              bigNumberify(await contract.functions[functionName](...test.in))
+              await contract.functions[functionName](...test.in)
             ).to.deep.equal(bigNumberify(test.out))
           }
         })

From 93f81c3cab4eeb4a740786309ecb02773370b547 Mon Sep 17 00:00:00 2001
From: Maurelian <maurelian@protonmail.ch>
Date: Thu, 15 Apr 2021 22:15:37 -0400
Subject: [PATCH 7/7] Update .changeset/ten-baboons-compete.md

---
 .changeset/ten-baboons-compete.md | 1 -
 1 file changed, 1 deletion(-)

diff --git a/.changeset/ten-baboons-compete.md b/.changeset/ten-baboons-compete.md
index c7acd3945d47..66a3b3f6af3a 100644
--- a/.changeset/ten-baboons-compete.md
+++ b/.changeset/ten-baboons-compete.md
@@ -2,7 +2,6 @@
 "@eth-optimism/contracts": minor
 ---
 
-- Remove ETH_SIGNED_MESSAGE and standardize on EIP-155 messages
 - Reduce nonce size to uint64
 - Ban ovmCALLER opcode when it would return ZERO
 - Add value transfer in OVM_ECDSAContractAccount