Add method to sign arbitrary msg using bip322 (#184)

* Add method to arbitrary msg using bip322

itest/e2e_test.go

@@ -18,6 +18,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/babylonchain/babylon/crypto/bip322"
 	btcctypes "github.com/babylonchain/babylon/x/btccheckpoint/types"
 
 	staking "github.com/babylonchain/babylon/btcstaking"
@@ -1533,6 +1534,32 @@ func TestBitcoindWalletRpcApi(t *testing.T) {
 	require.Equal(t, walletcontroller.TxInChain, status)
 }
 
+func TestBitcoindWalletBip322Signing(t *testing.T) {
+	h := NewBitcoindHandler(t)
+	h.Start()
+	passphrase := "pass"
+
+	_ = h.CreateWallet("test-wallet", passphrase)
+	cfg, c := defaultStakerConfig(t, passphrase)
+
+	segwitAddress, err := c.GetNewAddress("")
+	require.NoError(t, err)
+
+	controller, err := walletcontroller.NewRpcWalletController(cfg)
+	require.NoError(t, err)
+
+	err = controller.UnlockWallet(30)
+	require.NoError(t, err)
+
+	msg := []byte("test message")
+
+	bip322Signature, err := controller.SignBip322NativeSegwit(msg, segwitAddress)
+	require.NoError(t, err)
+
+	err = bip322.Verify(msg, bip322Signature, segwitAddress, regtestParams)
+	require.NoError(t, err)
+}
+
 func TestSendingStakingTransaction_Restaking(t *testing.T) {
 	// need to have at least 300 block on testnet as only then segwit is activated.
 	// Mature output is out which has 100 confirmations, which means 200mature outputs

walletcontroller/client.go

@@ -1,13 +1,16 @@
 package walletcontroller
 
 import (
+	"encoding/hex"
 	"fmt"
 	"sort"
 
+	"github.com/babylonchain/babylon/crypto/bip322"
 	"github.com/babylonchain/btc-staker/stakercfg"
 	scfg "github.com/babylonchain/btc-staker/stakercfg"
 	"github.com/babylonchain/btc-staker/types"
 	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/btcjson"
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
@@ -256,3 +259,44 @@ func (w *RpcWalletController) TxDetails(txHash *chainhash.Hash, pkScript []byte)
 		return nil, TxNotFound, fmt.Errorf("invalid bitcoin backend")
 	}
 }
+
+// SignBip322NativeSegwit signs arbitrary message using bip322 signing scheme.
+// To work properly:
+// - wallet must be unlocked
+// - address must be under wallet control
+// - address must be native segwit address
+func (w *RpcWalletController) SignBip322NativeSegwit(msg []byte, address btcutil.Address) (wire.TxWitness, error) {
+	toSpend, err := bip322.GetToSpendTx(msg, address)
+
+	if err != nil {
+		return nil, fmt.Errorf("failed to bip322 to spend tx: %w", err)
+	}
+
+	if !txscript.IsPayToWitnessPubKeyHash(toSpend.TxOut[0].PkScript) {
+		return nil, fmt.Errorf("Bip322NativeSegwit support only native segwit addresses")
+	}
+
+	toSpendhash := toSpend.TxHash()
+
+	toSign := bip322.GetToSignTx(toSpend)
+
+	amt := float64(0)
+	signed, all, err := w.SignRawTransactionWithWallet2(toSign, []btcjson.RawTxWitnessInput{
+		{
+			Txid:         toSpendhash.String(),
+			Vout:         0,
+			ScriptPubKey: hex.EncodeToString(toSpend.TxOut[0].PkScript),
+			Amount:       &amt,
+		},
+	})
+
+	if err != nil {
+		return nil, fmt.Errorf("failed to sign raw transaction while creating bip322 signature: %w", err)
+	}
+
+	if !all {
+		return nil, fmt.Errorf("failed to create bip322 signature, address %s is not under wallet control", address)
+	}
+
+	return signed.TxIn[0].Witness, nil
+}

walletcontroller/interface.go

@@ -36,4 +36,5 @@ type WalletController interface {
 	SendRawTransaction(tx *wire.MsgTx, allowHighFees bool) (*chainhash.Hash, error)
 	ListOutputs(onlySpendable bool) ([]Utxo, error)
 	TxDetails(txHash *chainhash.Hash, pkScript []byte) (*notifier.TxConfirmation, TxStatus, error)
+	SignBip322NativeSegwit(msg []byte, address btcutil.Address) (wire.TxWitness, error)
 }