Merge pull request #11 from iden3/fix/issue-9

Fix/issue #9

poseidon/poseidon.go

@@ -101,7 +101,7 @@ func checkAllDifferent(v []*big.Int) bool {
 
 // ark computes Add-Round Key, from the paper https://eprint.iacr.org/2019/458.pdf
 func ark(state []*big.Int, c *big.Int) []*big.Int {
-	for i := 0; i < len(state); i++ {
+	for i := 0; i < T; i++ {
 		state[i] = constants.fqR.Add(state[i], c)
 	}
 	return state
@@ -167,16 +167,17 @@ func Hash(arr []*big.Int) (*big.Int, error) {
 	}
 
 	r := constants.fqR.Zero()
-	for i := 0; i < len(arr); i = i + 5 {
-		var fiveElems [5]*big.Int
-		for j := 0; j < 5; j++ {
+	for i := 0; i < len(arr); i = i + T - 1 {
+		var toHash [T]*big.Int
+		for j := 0; j < T-1; j++ {
 			if i+j < len(arr) {
-				fiveElems[j] = arr[i+j]
+				toHash[j] = arr[i+j]
 			} else {
-				fiveElems[j] = _constants.Zero
+				toHash[j] = _constants.Zero
 			}
 		}
-		ph, err := PoseidonHash(fiveElems[:])
+		toHash[T-1] = r
+		ph, err := PoseidonHash(toHash[:])
 		if err != nil {
 			return nil, err
 		}

poseidon/poseidon_test.go

@@ -43,7 +43,7 @@ func TestPoseidon(t *testing.T) {
 	}
 	hmsg, err := Hash(msgElems)
 	assert.Nil(t, err)
-	assert.Equal(t, "11821124228916291136371255062457365369197326845706357273715164664419275913793", hmsg.String())
+	assert.Equal(t, "19204466598658860237115179437116112945222240370078952939676636700594938553268", hmsg.String())
 
 	msg2 := []byte("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Lorem ipsum dolor sit amet.")
 	msg2Elems := make([]*big.Int, 0, len(msg2)/n+1)
@@ -59,11 +59,11 @@ func TestPoseidon(t *testing.T) {
 	}
 	hmsg2, err := Hash(msg2Elems)
 	assert.Nil(t, err)
-	assert.Equal(t, "10747013384255785702102976082726575658403084163954725275481577373644732938016", hmsg2.String())
+	assert.Equal(t, "11846976426841208067103690249139614816718727366915557488657094868020932500524", hmsg2.String())
 
 	hmsg2, err = HashBytes(msg2)
 	assert.Nil(t, err)
-	assert.Equal(t, "10747013384255785702102976082726575658403084163954725275481577373644732938016", hmsg2.String())
+	assert.Equal(t, "11846976426841208067103690249139614816718727366915557488657094868020932500524", hmsg2.String())
 }
 
 func TestPoseidonBrokenChunks(t *testing.T) {