From 4dad36fa710c9ae1f0b7c34e04f2058f55d11755 Mon Sep 17 00:00:00 2001
From: Matt Yang <matt.yang@smartcontract.com>
Date: Tue, 19 Sep 2023 16:51:46 -0400
Subject: [PATCH] adding comments on hashing

---
 contracts/src/v0.8/ccip/libraries/Internal.sol | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/contracts/src/v0.8/ccip/libraries/Internal.sol b/contracts/src/v0.8/ccip/libraries/Internal.sol
index a56ed32559..a8988c8a6d 100644
--- a/contracts/src/v0.8/ccip/libraries/Internal.sol
+++ b/contracts/src/v0.8/ccip/libraries/Internal.sol
@@ -84,6 +84,8 @@ library Internal {
   bytes32 internal constant EVM_2_EVM_MESSAGE_HASH = keccak256("EVM2EVMMessageHash");
 
   function _hash(EVM2EVMMessage memory original, bytes32 metadataHash) internal pure returns (bytes32) {
+    // Fixed-size message fields are included in nested hash to reduce stack pressure.
+    // This hashing scheme is also used by RMN. If changing it, please notify RMN.
     return
       keccak256(
         abi.encode(