From 08783e5cb46f3c07afab2ea1a74048b6a1c7ee28 Mon Sep 17 00:00:00 2001
From: GG <863867759@qq.com>
Date: Mon, 8 Apr 2024 16:56:17 +0800
Subject: [PATCH] feat: support bitcoin func `signMessage`

---
 core/btc/account.go      | 50 ++++++++++++++++++++++++++++++++++++++++
 core/btc/account_test.go | 17 ++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/core/btc/account.go b/core/btc/account.go
index 94cdae8..7f56fc5 100644
--- a/core/btc/account.go
+++ b/core/btc/account.go
@@ -1,13 +1,18 @@
 package btc
 
 import (
+	"bytes"
+	"encoding/base64"
 	"fmt"
 
 	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/btcec/v2/ecdsa"
 	"github.com/btcsuite/btcd/btcec/v2/schnorr"
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/txscript"
+	"github.com/btcsuite/btcd/wire"
 	"github.com/centrifuge/go-substrate-rpc-client/v4/types"
 	"github.com/coming-chat/wallet-SDK/core/base"
 	"github.com/tyler-smith/go-bip39"
@@ -251,6 +256,51 @@ func (a *Account) SignHex(messageHex string, password string) (*base.OptionalStr
 	return nil, base.ErrUnsupportedFunction
 }
 
+// SignMessage
+// https://developer.bitcoin.org/reference/rpc/signmessage.html
+// @param msg The message to create a signature of.
+// @return The signature of the message encoded in base64.
+func (a *Account) SignMessage(msg string) (*base.OptionalString, error) {
+	msgHash := messageHash(msg)
+
+	signbytes, err := ecdsa.SignCompact(a.privateKey, msgHash, true)
+	if err != nil {
+		return nil, err
+	}
+	signature := base64.StdEncoding.EncodeToString(signbytes)
+	return base.NewOptionalString(signature), nil
+}
+
+func VerifySignature(pubkey, message, signature string) bool {
+	signBytes, err := base64.StdEncoding.DecodeString(signature)
+	if err != nil {
+		return false
+	}
+	pubBytes, err := types.HexDecodeString(pubkey)
+	if err != nil {
+		return false
+	}
+	pub, err := btcec.ParsePubKey(pubBytes)
+	if err != nil {
+		return false
+	}
+
+	msgHash := messageHash(message)
+	recoverPub, ok, err := ecdsa.RecoverCompact(signBytes, msgHash)
+	if err != nil || ok == false {
+		return false
+	}
+
+	return pub.IsEqual(recoverPub)
+}
+
+func messageHash(msg string) []byte {
+	var buf bytes.Buffer
+	_ = wire.WriteVarString(&buf, 0, "Bitcoin Signed Message:\n")
+	_ = wire.WriteVarString(&buf, 0, msg)
+	return chainhash.DoubleHashB(buf.Bytes())
+}
+
 // MARK - Implement the protocol AddressUtil
 
 // @param publicKey can start with 0x or not.
diff --git a/core/btc/account_test.go b/core/btc/account_test.go
index 463cce9..21b9eeb 100644
--- a/core/btc/account_test.go
+++ b/core/btc/account_test.go
@@ -325,3 +325,20 @@ func TestIsValidPrivateKey(t *testing.T) {
 	valid := IsValidPrivateKey("cTkZaPpb1pDdor36V5VY4uu5LE6tgzrjRADvrEXimEqWqvwRbfXY")
 	t.Log(valid)
 }
+
+func TestAccount_SignMessage(t *testing.T) {
+	acc, err := NewAccountWithMnemonic(testcase.M1, ChainMainnet)
+	require.Nil(t, err)
+	acc.AddressType = AddressTypeTaproot
+	t.Log(acc.Address())
+
+	// sign message
+	message := "hello world~"
+	signature, err := acc.SignMessage(message)
+	require.Nil(t, err)
+	t.Log("sign message result: ", signature.Value)
+
+	// check signature
+	valid := VerifySignature(acc.PublicKeyHex(), message, signature.Value)
+	t.Log("signature is valid: ", valid)
+}