Merge pull request #36 from iden3/feature/poseidon-update-reference-impl

Update Poseidon last changes of the reference impl

babyjub/babyjub.go

@@ -203,37 +203,24 @@ func PointCoordSign(c *big.Int) bool {
 	return c.Cmp(new(big.Int).Rsh(constants.Q, 1)) == 1
 }
 
-// PackPoint packs a point into a 32 byte array
-func PackPoint(ay *big.Int, sign bool) [32]byte {
-	leBuf := utils.BigIntLEBytes(ay)
+// PackSignY packs the given sign and the coordinate Y of a point into a 32
+// byte array. This method does not check that the values belong to a valid
+// Point in the curve.
+func PackSignY(sign bool, y *big.Int) [32]byte {
+	leBuf := utils.BigIntLEBytes(y)
 	if sign {
 		leBuf[31] = leBuf[31] | 0x80 //nolint:gomnd
 	}
 	return leBuf
 }
 
-// Compress the point into a 32 byte array that contains the y coordinate in
-// little endian and the sign of the x coordinate.
-func (p *Point) Compress() [32]byte {
-	sign := PointCoordSign(p.X)
-	return PackPoint(p.Y, sign)
-}
-
-// Decompress a compressed Point into p, and also returns the decompressed
-// Point.  Returns error if the compressed Point is invalid.
-func (p *Point) Decompress(leBuf [32]byte) (*Point, error) {
-	var sign bool
-	sign, p.Y = CompressedPointToSignAndY(leBuf)
-	return PointFromSignAndY(sign, p.Y)
-}
-
-// CompressedPointToSignAndY returns the sign and coordinate Y from a given
-// compressed point. This method does not check that the Point belongs to the
-// BabyJubJub curve, thus does not return error in such case. This method is
-// intended to obtain the sign and the Y coordinate without checking if the
-// point belongs to the curve, if the objective is to uncompress a point
-// Decompress method should be used instead.
-func CompressedPointToSignAndY(leBuf [32]byte) (bool, *big.Int) {
+// UnpackSignY returns the sign and coordinate Y from a given compressed point.
+// This method does not check that the Point belongs to the BabyJubJub curve,
+// thus does not return error in such case. This method is intended to obtain
+// the sign and the Y coordinate without checking if the point belongs to the
+// curve, if the objective is to uncompress a point, Decompress method should
+// be used instead.
+func UnpackSignY(leBuf [32]byte) (bool, *big.Int) {
 	sign := false
 	y := big.NewInt(0)
 	if (leBuf[31] & 0x80) != 0x00 { //nolint:gomnd
@@ -244,6 +231,21 @@ func CompressedPointToSignAndY(leBuf [32]byte) (bool, *big.Int) {
 	return sign, y
 }
 
+// Compress the point into a 32 byte array that contains the y coordinate in
+// little endian and the sign of the x coordinate.
+func (p *Point) Compress() [32]byte {
+	sign := PointCoordSign(p.X)
+	return PackSignY(sign, p.Y)
+}
+
+// Decompress a compressed Point into p, and also returns the decompressed
+// Point.  Returns error if the compressed Point is invalid.
+func (p *Point) Decompress(leBuf [32]byte) (*Point, error) {
+	var sign bool
+	sign, p.Y = UnpackSignY(leBuf)
+	return PointFromSignAndY(sign, p.Y)
+}
+
 // PointFromSignAndY returns a Point from a Sign and the Y coordinate
 func PointFromSignAndY(sign bool, y *big.Int) (*Point, error) {
 	var p Point

babyjub/babyjub_test.go

@@ -218,6 +218,26 @@ func TestPointFromSignAndy(t *testing.T) {
 	assert.Equal(t, p.Y.String(), p2.Y.String())
 }
 
+func TestPackAndUnpackSignY(t *testing.T) {
+	x := utils.NewIntFromString(
+		"17777552123799933955779906779655732241715742912184938656739573121738514868268")
+	y := utils.NewIntFromString(
+		"2626589144620713026669568689430873010625803728049924121243784502389097019475")
+	p := &Point{X: x, Y: y}
+	pComp := p.Compress()
+
+	s, y := UnpackSignY(pComp)
+
+	pComp2 := PackSignY(s, y)
+	assert.Equal(t, pComp, pComp2)
+
+	emptyPointComp := [32]byte{}
+	s, y = UnpackSignY(emptyPointComp)
+
+	pComp2 = PackSignY(s, y)
+	assert.Equal(t, emptyPointComp, pComp2)
+}
+
 func TestCompressDecompress1(t *testing.T) {
 	x := utils.NewIntFromString(
 		"17777552123799933955779906779655732241715742912184938656739573121738514868268")

babyjub/eddsa_test.go

@@ -97,7 +97,7 @@ func TestSignVerifyPoseidon(t *testing.T) {
 		"15383486972088797283337779941324724402501462225528836549661220478783371668959",
 		sig.R8.Y.String())
 	assert.Equal(t,
-		"1398758333392199195742243841591064350253744445503462896781493968760929513778",
+		"1672775540645840396591609181675628451599263765380031905495115170613215233181",
 		sig.S.String())
 
 	ok := pk.VerifyPoseidon(msg, sig)
@@ -109,7 +109,7 @@ func TestSignVerifyPoseidon(t *testing.T) {
 
 	assert.Equal(t, ""+
 		"dfedb4315d3f2eb4de2d3c510d7a987dcab67089c8ace06308827bf5bcbe02a2"+
-		"32f16b0f2f4c4e1169aa59685637e1429b6581a9531d058d65f4ab224eab1703",
+		"9d043ece562a8f82bfc0adb640c0107a7d3a27c1c7c1a6179a0da73de5c1b203",
 		hex.EncodeToString(sigBuf[:]))
 
 	ok = pk.VerifyPoseidon(msg, sig2)
@@ -139,7 +139,7 @@ func TestCompressDecompress(t *testing.T) {
 
 func TestSignatureCompScannerValuer(t *testing.T) {
 	privK := NewRandPrivKey()
-	var value driver.Valuer //nolint:gosimple this is done to ensure interface compability
+	var value driver.Valuer //nolint:gosimple this is done to ensure interface compatibility
 	value = privK.SignPoseidon(big.NewInt(674238462)).Compress()
 	scan := privK.SignPoseidon(big.NewInt(1)).Compress()
 	fromDB, err := value.Value()

poseidon/poseidon.go

@@ -47,7 +47,7 @@ func mix(state []*ff.Element, newState []*ff.Element, m [][]*ff.Element) {
 	for i := 0; i < len(state); i++ {
 		newState[i].SetUint64(0)
 		for j := 0; j < len(state); j++ {
-			mul.Mul(m[j][i], state[j])
+			mul.Mul(m[i][j], state[j])
 			newState[i].Add(newState[i], mul)
 		}
 	}
@@ -64,8 +64,8 @@ func Hash(inpBI []*big.Int) (*big.Int, error) {
 	}
 	inp := utils.BigIntArrayToElementArray(inpBI[:])
 	state := make([]*ff.Element, t)
-	copy(state[:], inp[:])
-	state[len(state)-1] = zero()
+	state[0] = zero()
+	copy(state[1:], inp[:])
 
 	nRoundsF := NROUNDSF
 	nRoundsP := NROUNDSP[t-2]
@@ -79,10 +79,8 @@ func Hash(inpBI []*big.Int) (*big.Int, error) {
 	for i := 0; i < nRoundsF+nRoundsP; i++ {
 		ark(state, c.c[t-2], i*t)
 		sbox(nRoundsF, nRoundsP, state, i)
-		if i < nRoundsF+nRoundsP-1 {
-			mix(state, newState, c.m[t-2])
-			state, newState = newState, state
-		}
+		mix(state, newState, c.m[t-2])
+		state, newState = newState, state
 	}
 	rE := state[0]
 	r := big.NewInt(0)

poseidon/poseidon_test.go

@@ -25,24 +25,24 @@ func TestPoseidonHash(t *testing.T) {
 	h, err := Hash([]*big.Int{b1})
 	assert.Nil(t, err)
 	assert.Equal(t,
-		"11043376183861534927536506085090418075369306574649619885724436265926427398571",
+		"18586133768512220936620570745912940619677854269274689475585506675881198879027",
 		h.String())
 
 	h, err = Hash([]*big.Int{b1, b2})
 	assert.Nil(t, err)
 	assert.Equal(t,
-		"17117985411748610629288516079940078114952304104811071254131751175361957805920",
+		"7853200120776062878684798364095072458815029376092732009249414926327459813530",
 		h.String())
 
 	h, err = Hash([]*big.Int{b1, b2, b0, b0, b0})
 	assert.Nil(t, err)
 	assert.Equal(t,
-		"3975478831357328722254985704342968745327876719981393787143845259590563829094",
+		"1018317224307729531995786483840663576608797660851238720571059489595066344487",
 		h.String())
 	h, err = Hash([]*big.Int{b1, b2, b0, b0, b0, b0})
 	assert.Nil(t, err)
 	assert.Equal(t,
-		"19772360636270345724087386688434825760738403416279047262510528378903625000110",
+		"15336558801450556532856248569924170992202208561737609669134139141992924267169",
 		h.String())
 
 	b3 := big.NewInt(3)
@@ -50,12 +50,12 @@ func TestPoseidonHash(t *testing.T) {
 	h, err = Hash([]*big.Int{b3, b4, b0, b0, b0})
 	assert.Nil(t, err)
 	assert.Equal(t,
-		"3181200837746671699652342497997860344148947482942465819251904554707352676086",
+		"5811595552068139067952687508729883632420015185677766880877743348592482390548",
 		h.String())
 	h, err = Hash([]*big.Int{b3, b4, b0, b0, b0, b0})
 	assert.Nil(t, err)
 	assert.Equal(t,
-		"8386348873272147968934270337233829407378789978142456170950021426339096575008",
+		"12263118664590987767234828103155242843640892839966517009184493198782366909018",
 		h.String())
 
 	b5 := big.NewInt(5)
@@ -63,7 +63,7 @@ func TestPoseidonHash(t *testing.T) {
 	h, err = Hash([]*big.Int{b1, b2, b3, b4, b5, b6})
 	assert.Nil(t, err)
 	assert.Equal(t,
-		"5202465217520500374834597824465244016759843635092906214933648999760272616044",
+		"20400040500897583745843009878988256314335038853985262692600694741116813247201",
 		h.String())
 }