@@ -222,11 +222,13 @@ r := utils.SetBigIntFromLEBytes(new(big.Int), rBuf) // r = H(H_{32..63}(k), msg)
 	r.Mod(r, SubOrder)
 	R8 := NewPoint().Mul(r, B8) // R8 = r * 8 * B
 	A := k.Public().Point()
+
 	hmInput := [poseidon.T]*big.Int{R8.X, R8.Y, A.X, A.Y, msg, big.NewInt(int64(0))}
 	hm, err := poseidon.PoseidonHash(hmInput) // hm = H1(8*R.x, 8*R.y, A.x, A.y, msg)
 	if err != nil {
 		panic(err)
 	}
+
 	S := new(big.Int).Lsh(k.Scalar().BigInt(), 3)
 	S = S.Mul(hm, S)
 	S.Add(r, S)

@@ -0,0 +1,5 @@
+package ff
+
+func NewElement() *Element {
+	return &Element{}
+}

@@ -5,6 +5,7 @@ "errors"
 	"math/big"
 	"strconv"
 
+	"github.com/iden3/go-iden3-crypto/constants"
 	"github.com/iden3/go-iden3-crypto/ff"
 	"github.com/iden3/go-iden3-crypto/utils"
 	"golang.org/x/crypto/blake2b"
@@ -19,7 +20,11 @@ var constC []*ff.Element
 var constM [T][T]*ff.Element
 
 func Zero() *ff.Element {
-	return utils.NewElement().SetZero()
+	return ff.NewElement().SetZero()
+}
+
+func modQ(v *big.Int) {
+	v.Mod(v, constants.Q)
 }
 
 func init() {
@@ -32,7 +37,7 @@ res := make([]*ff.Element, n)
 	hash := blake2b.Sum256([]byte(seed))
 	for i := 0; i < n; i++ {
 		hashBigInt := big.NewInt(int64(0))
-		res[i] = utils.NewElement().SetBigInt(utils.SetBigIntFromLEBytes(hashBigInt, hash[:]))
+		res[i] = ff.NewElement().SetBigInt(utils.SetBigIntFromLEBytes(hashBigInt, hash[:]))
 		hash = blake2b.Sum256(hash[:])
 	}
 	return res
@@ -57,7 +62,7 @@ }
 	var m [T][T]*ff.Element
 	for i := 0; i < T; i++ {
 		for j := 0; j < T; j++ {
-			m[i][j] = utils.NewElement().Sub(cauchyMatrix[i], cauchyMatrix[T+j])
+			m[i][j] = ff.NewElement().Sub(cauchyMatrix[i], cauchyMatrix[T+j])
 			m[i][j].Inverse(m[i][j])
 		}
 	}
@@ -66,7 +71,7 @@ }
 
 func checkAllDifferent(v []*ff.Element) bool {
 	for i := 0; i < len(v); i++ {
-		if v[i].Equal(utils.NewElement().SetZero()) {
+		if v[i].Equal(ff.NewElement().SetZero()) {
 			return false
 		}
 		for j := i + 1; j < len(v); j++ {
@@ -117,13 +122,14 @@ }
 }
 
 // PoseidonHash computes the Poseidon hash for the given inputs
-func PoseidonHash(inp [T]*ff.Element) (*ff.Element, error) {
-	if !utils.CheckElementArrayInField(inp[:]) {
+func PoseidonHash(inpBI [T]*big.Int) (*big.Int, error) {
+	if !utils.CheckBigIntArrayInField(inpBI[:]) {
 		return nil, errors.New("inputs values not inside Finite Field")
 	}
+	inp := utils.BigIntArrayToElementArray(inpBI[:])
 	state := [T]*ff.Element{}
 	for i := 0; i < T; i++ {
-		state[i] = utils.NewElement().Set(inp[i])
+		state[i] = ff.NewElement().Set(inp[i])
 	}
 
 	// ARK --> SBox --> M, https://eprint.iacr.org/2019/458.pdf pag.5
@@ -137,19 +143,18 @@ sbox(state, i)
 		mix(state, newState, constM)
 		state, newState = newState, state
 	}
-	return state[0], nil
+	rE := state[0]
+	r := big.NewInt(0)
+	rE.ToBigIntRegular(r)
+	return r, nil
 }
 
 // Hash performs the Poseidon hash over a ff.Element array
 // in chunks of 5 elements
-func Hash(arr []*ff.Element) (*ff.Element, error) {
-	if !utils.CheckElementArrayInField(arr) {
-		return nil, errors.New("inputs values not inside Finite Field")
-	}
-
-	r := utils.NewElement().SetOne()
+func Hash(arr []*big.Int) (*big.Int, error) {
+	r := big.NewInt(int64(1))
 	for i := 0; i < len(arr); i = i + T - 1 {
-		var toHash [T]*ff.Element
+		var toHash [T]*big.Int
 		j := 0
 		for ; j < T-1; j++ {
 			if i+j >= len(arr) {
@@ -160,14 +165,14 @@ }
 		toHash[j] = r
 		j++
 		for ; j < T; j++ {
-			toHash[j] = Zero()
+			toHash[j] = big.NewInt(0)
 		}
 
 		ph, err := PoseidonHash(toHash)
 		if err != nil {
 			return nil, err
 		}
-		r.Add(r, ph)
+		modQ(r.Add(r, ph))
 	}
 
 	return r, nil
@@ -175,19 +180,19 @@ }
 
 // HashBytes hashes a msg byte slice by blocks of 31 bytes encoded as
 // little-endian
-func HashBytes(b []byte) (*ff.Element, error) {
+func HashBytes(b []byte) (*big.Int, error) {
 	n := 31
-	bElems := make([]*ff.Element, 0, len(b)/n+1)
+	bElems := make([]*big.Int, 0, len(b)/n+1)
 	for i := 0; i < len(b)/n; i++ {
 		v := big.NewInt(int64(0))
 		utils.SetBigIntFromLEBytes(v, b[n*i:n*(i+1)])
-		bElems = append(bElems, utils.NewElement().SetBigInt(v))
+		bElems = append(bElems, v)
 
 	}
 	if len(b)%n != 0 {
 		v := big.NewInt(int64(0))
 		utils.SetBigIntFromLEBytes(v, b[(len(b)/n)*n:])
-		bElems = append(bElems, utils.NewElement().SetBigInt(v))
+		bElems = append(bElems, v)
 	}
 	return Hash(bElems)
 }

@@ -5,7 +5,6 @@ "encoding/hex"
 	"math/big"
 	"testing"
 
-	"github.com/iden3/go-iden3-crypto/ff"
 	"github.com/iden3/go-iden3-crypto/utils"
 	"github.com/stretchr/testify/assert"
 	"golang.org/x/crypto/blake2b"
@@ -17,46 +16,58 @@ assert.Equal(t, "e57ba154fb2c47811dc1a2369b27e25a44915b4e4ece4eb8ec74850cb78e01b1", hex.EncodeToString(h[:]))
 }
 
 func TestPoseidon(t *testing.T) {
-	b1 := utils.NewElement().SetUint64(1)
-	b2 := utils.NewElement().SetUint64(2)
-	h, err := Hash([]*ff.Element{b1, b2})
+	b1 := big.NewInt(1)
+	b2 := big.NewInt(2)
+	h, err := Hash([]*big.Int{b1, b2})
 	assert.Nil(t, err)
 	assert.Equal(t, "4932297968297298434239270129193057052722409868268166443802652458940273154855", h.String())
 
-	b3 := utils.NewElement().SetUint64(3)
-	b4 := utils.NewElement().SetUint64(4)
-	h, err = Hash([]*ff.Element{b3, b4})
+	b3 := big.NewInt(3)
+	b4 := big.NewInt(4)
+	h, err = Hash([]*big.Int{b3, b4})
 	assert.Nil(t, err)
 	assert.Equal(t, "4635491972858758537477743930622086396911540895966845494943021655521913507504", h.String())
 
+	b5 := big.NewInt(5)
+	b6 := big.NewInt(6)
+	b7 := big.NewInt(7)
+	b8 := big.NewInt(8)
+	b9 := big.NewInt(9)
+	b10 := big.NewInt(10)
+	b11 := big.NewInt(11)
+	b12 := big.NewInt(12)
+	h, err = Hash([]*big.Int{b1, b2, b3, b4, b5, b6, b7, b8, b9, b10, b11, b12})
+	assert.Nil(t, err)
+	assert.Equal(t, "15278801138972282646981503374384603641625274360649669926363020545395022098027", h.String())
+
 	msg := []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.")
 	n := 31
-	msgElems := make([]*ff.Element, 0, len(msg)/n+1)
+	msgElems := make([]*big.Int, 0, len(msg)/n+1)
 	for i := 0; i < len(msg)/n; i++ {
 		v := new(big.Int)
 		utils.SetBigIntFromLEBytes(v, msg[n*i:n*(i+1)])
-		msgElems = append(msgElems, utils.NewElement().SetBigInt(v))
+		msgElems = append(msgElems, v)
 	}
 	if len(msg)%n != 0 {
 		v := new(big.Int)
 		utils.SetBigIntFromLEBytes(v, msg[(len(msg)/n)*n:])
-		msgElems = append(msgElems, utils.NewElement().SetBigInt(v))
+		msgElems = append(msgElems, v)
 	}
 	hmsg, err := Hash(msgElems)
 	assert.Nil(t, err)
 	assert.Equal(t, "16019700159595764790637132363672701294192939959594423814006267756172551741065", 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([]*ff.Element, 0, len(msg2)/n+1)
+	msg2Elems := make([]*big.Int, 0, len(msg2)/n+1)
 	for i := 0; i < len(msg2)/n; i++ {
 		v := new(big.Int)
 		utils.SetBigIntFromLEBytes(v, msg2[n*i:n*(i+1)])
-		msg2Elems = append(msg2Elems, utils.NewElement().SetBigInt(v))
+		msg2Elems = append(msg2Elems, v)
 	}
 	if len(msg2)%n != 0 {
 		v := new(big.Int)
 		utils.SetBigIntFromLEBytes(v, msg2[(len(msg2)/n)*n:])
-		msg2Elems = append(msg2Elems, utils.NewElement().SetBigInt(v))
+		msg2Elems = append(msg2Elems, v)
 	}
 	hmsg2, err := Hash(msg2Elems)
 	assert.Nil(t, err)
@@ -68,29 +79,29 @@ assert.Equal(t, "2978613163687734485261639854325792381691890647104372645321246092227111432722", hmsg2.String())
 }
 
 func TestPoseidonBrokenChunks(t *testing.T) {
-	h1, err := Hash([]*ff.Element{utils.NewElement().SetUint64(0), utils.NewElement().SetUint64(1), utils.NewElement().SetUint64(2), utils.NewElement().SetUint64(3), utils.NewElement().SetUint64(4),
-		utils.NewElement().SetUint64(5), utils.NewElement().SetUint64(6), utils.NewElement().SetUint64(7), utils.NewElement().SetUint64(8), utils.NewElement().SetUint64(9)})
+	h1, err := Hash([]*big.Int{big.NewInt(0), big.NewInt(1), big.NewInt(2), big.NewInt(3), big.NewInt(4),
+		big.NewInt(5), big.NewInt(6), big.NewInt(7), big.NewInt(8), big.NewInt(9)})
 	assert.Nil(t, err)
-	h2, err := Hash([]*ff.Element{utils.NewElement().SetUint64(5), utils.NewElement().SetUint64(6), utils.NewElement().SetUint64(7), utils.NewElement().SetUint64(8), utils.NewElement().SetUint64(9),
-		utils.NewElement().SetUint64(0), utils.NewElement().SetUint64(1), utils.NewElement().SetUint64(2), utils.NewElement().SetUint64(3), utils.NewElement().SetUint64(4)})
+	h2, err := Hash([]*big.Int{big.NewInt(5), big.NewInt(6), big.NewInt(7), big.NewInt(8), big.NewInt(9),
+		big.NewInt(0), big.NewInt(1), big.NewInt(2), big.NewInt(3), big.NewInt(4)})
 	assert.Nil(t, err)
 	assert.NotEqual(t, h1, h2)
 }
 
 func TestPoseidonBrokenPadding(t *testing.T) {
-	h1, err := Hash([]*ff.Element{utils.NewElement().SetUint64(1)})
+	h1, err := Hash([]*big.Int{big.NewInt(int64(1))})
 	assert.Nil(t, err)
-	h2, err := Hash([]*ff.Element{utils.NewElement().SetUint64(1), utils.NewElement().SetUint64(0)})
+	h2, err := Hash([]*big.Int{big.NewInt(int64(1)), big.NewInt(int64(0))})
 	assert.Nil(t, err)
 	assert.NotEqual(t, h1, h2)
 }
 
 func BenchmarkPoseidon(b *testing.B) {
-	b12 := utils.NewElement().SetUint64(12)
-	b45 := utils.NewElement().SetUint64(45)
-	b78 := utils.NewElement().SetUint64(78)
-	b41 := utils.NewElement().SetUint64(41)
-	bigArray4 := []*ff.Element{b12, b45, b78, b41}
+	b12 := big.NewInt(int64(12))
+	b45 := big.NewInt(int64(45))
+	b78 := big.NewInt(int64(78))
+	b41 := big.NewInt(int64(41))
+	bigArray4 := []*big.Int{b12, b45, b78, b41}
 
 	for i := 0; i < b.N; i++ {
 		Hash(bigArray4)
@@ -98,11 +109,12 @@ }
 }
 
 func BenchmarkPoseidonLarge(b *testing.B) {
-	b12 := utils.NewElement().SetString("11384336176656855268977457483345535180380036354188103142384839473266348197733")
-	b45 := utils.NewElement().SetString("11384336176656855268977457483345535180380036354188103142384839473266348197733")
-	b78 := utils.NewElement().SetString("11384336176656855268977457483345535180380036354188103142384839473266348197733")
-	b41 := utils.NewElement().SetString("11384336176656855268977457483345535180380036354188103142384839473266348197733")
-	bigArray4 := []*ff.Element{b12, b45, b78, b41}
+	b12 := utils.NewIntFromString("11384336176656855268977457483345535180380036354188103142384839473266348197733")
+	b45 := utils.NewIntFromString("11384336176656855268977457483345535180380036354188103142384839473266348197733")
+	b78 := utils.NewIntFromString("11384336176656855268977457483345535180380036354188103142384839473266348197733")
+	b41 := utils.NewIntFromString("11384336176656855268977457483345535180380036354188103142384839473266348197733")
+
+	bigArray4 := []*big.Int{b12, b45, b78, b41}
 
 	for i := 0; i < b.N; i++ {
 		Hash(bigArray4)

@@ -108,18 +108,10 @@ }
 	return true
 }
 
-// CheckElementArrayInField checks if given *ff.Element fits in a Field Q element
-func CheckElementArrayInField(arr []*ff.Element) bool {
-	for _, aE := range arr {
-		a := big.NewInt(0)
-		aE.ToBigIntRegular(a)
-		if !CheckBigIntInField(a) {
-			return false
-		}
+func BigIntArrayToElementArray(bi []*big.Int) []*ff.Element {
+	var o []*ff.Element
+	for i := range bi {
+		o = append(o, ff.NewElement().SetBigInt(bi[i]))
 	}
-	return true
-}
-
-func NewElement() *ff.Element {
-	return &ff.Element{0, 0, 0, 0}
+	return o
 }