Merge pull request #436 from hermeznetwork/feature/exit-proof-siblings

Update ExitProofs-Siblings padding

common/utils.go

@@ -1,12 +1,14 @@
 package common
 
 import (
+	"bytes"
 	"encoding/hex"
 	"math/big"
 
 	ethCommon "github.com/ethereum/go-ethereum/common"
 	"github.com/hermeznetwork/tracerr"
 	"github.com/iden3/go-iden3-crypto/babyjub"
+	"github.com/iden3/go-merkletree"
 )
 
 // SwapEndianness swaps the order of the bytes in the slice.
@@ -42,3 +44,21 @@ func BJJFromStringWithChecksum(s string) (babyjub.PublicKeyComp, error) {
 func CopyBigInt(a *big.Int) *big.Int {
 	return new(big.Int).SetBytes(a.Bytes())
 }
+
+// RmEndingZeroes is used to convert the Siblings from a CircomProof into
+// Siblings of a merkletree Proof compatible with the js version. This method
+// should be used only if it exist an already generated CircomProof compatible
+// with circom circuits and a CircomProof compatible with SmartContracts is
+// needed. If the proof is not generated yet, this method should not be needed
+// and should be used mt.GenerateSCVerifierProof to directly generate the
+// CircomProof for the SmartContracts.
+func RmEndingZeroes(siblings []*merkletree.Hash) []*merkletree.Hash {
+	pos := 0
+	for i := len(siblings) - 1; i >= 0; i-- {
+		if !bytes.Equal(siblings[i].Bytes(), merkletree.HashZero.Bytes()) {
+			pos = i + 1
+			break
+		}
+	}
+	return siblings[:pos]
+}

common/utils_test.go

@@ -4,7 +4,9 @@ import (
 	"encoding/hex"
 	"testing"
 
+	"github.com/iden3/go-merkletree"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestBJJFromStringWithChecksum(t *testing.T) {
@@ -22,3 +24,52 @@ func TestBJJFromStringWithChecksum(t *testing.T) {
 	assert.Equal(t, "2492816973395423007340226948038371729989170225696553239457870892535792679622", pk.X.String())
 	assert.Equal(t, "15238403086306505038849621710779816852318505119327426213168494964113886299863", pk.Y.String())
 }
+
+func TestRmEndingZeroes(t *testing.T) {
+	s0, err := merkletree.NewHashFromHex("0x0000000000000000000000000000000000000000000000000000000000000000")
+	require.NoError(t, err)
+	s1, err := merkletree.NewHashFromHex("0x0000000000000000000000000000000000000000000000000000000000000001")
+	require.NoError(t, err)
+	s2, err := merkletree.NewHashFromHex("0x0000000000000000000000000000000000000000000000000000000000000002")
+	require.NoError(t, err)
+
+	// expect cropped last zeroes
+	circomSiblings := []*merkletree.Hash{s0, s1, s0, s1, s1, s1, s2, s0, s0, s0, s0}
+	siblings := RmEndingZeroes(circomSiblings)
+	expected := []*merkletree.Hash{s0, s1, s0, s1, s1, s1, s2}
+	assert.Equal(t, expected, siblings)
+
+	// expect empty array when input is an empty array
+	siblings = RmEndingZeroes([]*merkletree.Hash{})
+	assert.Equal(t, []*merkletree.Hash{}, siblings)
+	// expect nil when input is nil
+	siblings = RmEndingZeroes(nil)
+	assert.Nil(t, siblings)
+
+	// cases when inputs are [x], [x,0], [0,x]
+	circomSiblings = []*merkletree.Hash{s1}
+	siblings = RmEndingZeroes(circomSiblings)
+	assert.Equal(t, []*merkletree.Hash{s1}, siblings)
+	circomSiblings = []*merkletree.Hash{s1, s0}
+	siblings = RmEndingZeroes(circomSiblings)
+	assert.Equal(t, []*merkletree.Hash{s1}, siblings)
+	circomSiblings = []*merkletree.Hash{s0, s1}
+	siblings = RmEndingZeroes(circomSiblings)
+	assert.Equal(t, []*merkletree.Hash{s0, s1}, siblings)
+
+	// expect empty array when input is all zeroes
+	circomSiblings = []*merkletree.Hash{s0}
+	siblings = RmEndingZeroes(circomSiblings)
+	assert.Equal(t, []*merkletree.Hash{}, siblings)
+	circomSiblings = []*merkletree.Hash{s0, s0}
+	siblings = RmEndingZeroes(circomSiblings)
+	assert.Equal(t, []*merkletree.Hash{}, siblings)
+	circomSiblings = []*merkletree.Hash{s0, s0, s0, s0, s0}
+	siblings = RmEndingZeroes(circomSiblings)
+	assert.Equal(t, []*merkletree.Hash{}, siblings)
+
+	// expect input equal to output when last element!=0
+	circomSiblings = []*merkletree.Hash{s0, s1, s0, s1, s1, s1, s2, s0, s0, s0, s0, s2}
+	siblings = RmEndingZeroes(circomSiblings)
+	assert.Equal(t, circomSiblings, siblings)
+}

db/statedb/statedb.go

@@ -328,7 +328,11 @@ func (s *StateDB) MTGetProof(idx common.Idx) (*merkletree.CircomVerifierProof, e
 	if s.MT == nil {
 		return nil, tracerr.Wrap(ErrStateDBWithoutMT)
 	}
-	return s.MT.GenerateCircomVerifierProof(idx.BigInt(), s.MT.Root())
+	p, err := s.MT.GenerateSCVerifierProof(idx.BigInt(), s.MT.Root())
+	if err != nil {
+		return nil, tracerr.Wrap(err)
+	}
+	return p, nil
 }
 
 // MTGetRoot returns the current root of the underlying Merkle Tree

go.mod

@@ -13,7 +13,7 @@ require (
 	github.com/gobuffalo/packr/v2 v2.8.1
 	github.com/hermeznetwork/tracerr v0.3.1-0.20201126162137-de9930d0cf29
 	github.com/iden3/go-iden3-crypto v0.0.6-0.20201221160344-58e589b6eb4c
-	github.com/iden3/go-merkletree v0.0.0-20201218120219-8f3905f15f89
+	github.com/iden3/go-merkletree v0.0.0-20201230093451-4280a9914f51
 	github.com/jinzhu/copier v0.0.0-20190924061706-b57f9002281a
 	github.com/jmoiron/sqlx v1.2.1-0.20200615141059-0794cb1f47ee
 	github.com/joho/godotenv v1.3.0

go.sum

@@ -309,8 +309,8 @@ github.com/huin/goutil v0.0.0-20170803182201-1ca381bf3150/go.mod h1:PpLOETDnJ0o3
 github.com/iden3/go-iden3-crypto v0.0.6-0.20201218111145-a2015adb2f1b/go.mod h1:oBgthFLboAWi9feaBUFy7OxEcyn9vA1khHSL/WwWFyg=
 github.com/iden3/go-iden3-crypto v0.0.6-0.20201221160344-58e589b6eb4c h1:D2u8FFYey6iFXLsqqJZ8R7ch8gZum+/b98whvoSDbyg=
 github.com/iden3/go-iden3-crypto v0.0.6-0.20201221160344-58e589b6eb4c/go.mod h1:oBgthFLboAWi9feaBUFy7OxEcyn9vA1khHSL/WwWFyg=
-github.com/iden3/go-merkletree v0.0.0-20201218120219-8f3905f15f89 h1:t7tnOTCtw12Rniyk98Hi4gOp0h5JPdzbNcLWCFNj98o=
+github.com/iden3/go-merkletree v0.0.0-20201230093451-4280a9914f51 h1:EqkLnC+JlOdX3hQnjq0u2JKcMMmmaQcpmG1udG6BTXw=
-github.com/iden3/go-merkletree v0.0.0-20201218120219-8f3905f15f89/go.mod h1:MCXbnyoFRwt+7aYHtzVSB3sZZcHLjDf7VZZ2Zqrhqrc=
+github.com/iden3/go-merkletree v0.0.0-20201230093451-4280a9914f51/go.mod h1:MCXbnyoFRwt+7aYHtzVSB3sZZcHLjDf7VZZ2Zqrhqrc=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/influxdata/influxdb v1.2.3-0.20180221223340-01288bdb0883/go.mod h1:qZna6X/4elxqT3yI9iZYdZrWWdeFOOprn86kgg4+IzY=
 github.com/influxdata/influxdb1-client v0.0.0-20190809212627-fc22c7df067e/go.mod h1:qj24IKcXYK6Iy9ceXlo3Tc+vtHo9lIhSX5JddghvEPo=

txprocessor/txprocessor.go

@@ -372,10 +372,11 @@ func (tp *TxProcessor) ProcessTxs(coordIdxs []common.Idx, l1usertxs, l1coordinat
 		exitAccount := exits[i].acc
 
 		// 0. generate MerkleProof
-		p, err := exitTree.GenerateCircomVerifierProof(exitIdx.BigInt(), nil)
+		p, err := exitTree.GenerateSCVerifierProof(exitIdx.BigInt(), nil)
 		if err != nil {
 			return nil, tracerr.Wrap(err)
 		}
+
 		// 1. generate common.ExitInfo
 		ei := common.ExitInfo{
 			AccountIdx:  exitIdx,