From dcd40f1943ceec7684bd7093efa2dee8bf676928 Mon Sep 17 00:00:00 2001
From: arnaubennassar <arnaubennassar5@gmail.com>
Date: Fri, 5 Mar 2021 15:31:52 +0100
Subject: [PATCH] Fix tx signature when toEthAddr starts with 0x0

---
 common/pooll2tx.go      |  4 +---
 common/pooll2tx_test.go | 27 +++++++++++++++++++++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/common/pooll2tx.go b/common/pooll2tx.go
index ac666ec..5021bfc 100644
--- a/common/pooll2tx.go
+++ b/common/pooll2tx.go
@@ -304,10 +304,8 @@ func (tx *PoolL2Tx) HashToSign(chainID uint16) (*big.Int, error) {
 		return nil, tracerr.Wrap(err)
 	}
 	copy(e1B[0:5], amountFloat40Bytes)
-	toEthAddr := EthAddrToBigInt(tx.ToEthAddr)
-	copy(e1B[5:25], toEthAddr.Bytes())
+	copy(e1B[5:25], tx.ToEthAddr[:])
 	e1 := new(big.Int).SetBytes(e1B[:])
-
 	rqToEthAddr := EthAddrToBigInt(tx.RqToEthAddr)
 
 	_, toBJJY := babyjub.UnpackSignY(tx.ToBJJ)
diff --git a/common/pooll2tx_test.go b/common/pooll2tx_test.go
index d321ba5..53cdc01 100644
--- a/common/pooll2tx_test.go
+++ b/common/pooll2tx_test.go
@@ -193,6 +193,33 @@ func TestVerifyTxSignature(t *testing.T) {
 	assert.True(t, tx.VerifySignature(chainID, sk.Public().Compress()))
 }
 
+func TestVerifyTxSignatureEthAddrWith0(t *testing.T) {
+	chainID := uint16(5)
+	var sk babyjub.PrivateKey
+	_, err := hex.Decode(sk[:],
+		[]byte("02f0b4f87065af3797aaaf934e8b5c31563c17f2272fa71bd0146535bfbb4184"))
+	assert.NoError(t, err)
+	tx := PoolL2Tx{
+		FromIdx:   10659,
+		ToIdx:     0,
+		ToEthAddr: ethCommon.HexToAddress("0x0004308BD15Ead4F1173624dC289DBdcC806a309"),
+		Amount:    big.NewInt(5000),
+		TokenID:   0,
+		Nonce:     946,
+		Fee:       231,
+	}
+	toSign, err := tx.HashToSign(chainID)
+	assert.NoError(t, err)
+
+	sig := sk.SignPoseidon(toSign)
+	assert.Equal(t,
+		"93ce988ecac87908513648d0d021d8ad56d3b504eb38204200f07a8f6c20551de9951397d3051143d4c71203205f8849cd7382d2bcf4bd10092c1e052bb40d01",
+		sig.Compress().String(),
+	)
+	tx.Signature = sig.Compress()
+	assert.True(t, tx.VerifySignature(chainID, sk.Public().Compress()))
+}
+
 func TestDecompressEmptyBJJComp(t *testing.T) {
 	pkComp := EmptyBJJComp
 	pk, err := pkComp.Decompress()