Poseidon Sponge Hash with different frame sizes (#52)

* Poseidon Sponge Hash with different frame sizes
* Update deps. Bump go version
* Update & fix linter.
* Refactor a bit.
* Reduce gc pressure

babyjub/babyjub.go

@@ -87,7 +87,7 @@ func (p *PointProjective) Affine() *Point {
 
 // Add computes the addition of two points in projective coordinates
 // representation
-func (p *PointProjective) Add(q *PointProjective, o *PointProjective) *PointProjective {
+func (p *PointProjective) Add(q, o *PointProjective) *PointProjective {
 	// add-2008-bbjlp
 	// https://hyperelliptic.org/EFD/g1p/auto-twisted-projective.html#doubling-dbl-2008-bbjlp
 	a := ff.NewElement().Mul(q.Z, o.Z)
@@ -209,7 +209,7 @@ func PointCoordSign(c *big.Int) bool {
 func PackSignY(sign bool, y *big.Int) [32]byte {
 	leBuf := utils.BigIntLEBytes(y)
 	if sign {
-		leBuf[31] = leBuf[31] | 0x80 //nolint:gomnd
+		leBuf[31] |= 0x80 //nolint:gomnd
 	}
 	return leBuf
 }
@@ -225,7 +225,7 @@ func UnpackSignY(leBuf [32]byte) (bool, *big.Int) {
 	y := big.NewInt(0)
 	if (leBuf[31] & 0x80) != 0x00 { //nolint:gomnd
 		sign = true
-		leBuf[31] = leBuf[31] & 0x7F //nolint:gomnd
+		leBuf[31] &= 0x7F //nolint:gomnd
 	}
 	utils.SetBigIntFromLEBytes(y, leBuf[:])
 	return sign, y

babyjub/eddsa.go

@@ -1,4 +1,5 @@
 // Package babyjub eddsa implements the EdDSA over the BabyJubJub curve
+//
 //nolint:gomnd
 package babyjub
 
@@ -16,9 +17,9 @@ import (
 // pruneBuffer prunes the buffer during key generation according to RFC 8032.
 // https://tools.ietf.org/html/rfc8032#page-13
 func pruneBuffer(buf *[32]byte) *[32]byte {
-	buf[0] = buf[0] & 0xF8
-	buf[31] = buf[31] & 0x7F
-	buf[31] = buf[31] | 0x40
+	buf[0] &= 0xF8
+	buf[31] &= 0x7F
+	buf[31] |= 0x40
 	return buf
 }
 
@@ -210,7 +211,7 @@ func (sComp *SignatureComp) Scan(src interface{}) error {
 	if len(srcB) != 64 {
 		return fmt.Errorf("can't scan []byte of len %d into Signature, want %d", len(srcB), 64)
 	}
-	copy(sComp[:], srcB[:])
+	copy(sComp[:], srcB)
 	return nil
 }
 
@@ -229,7 +230,7 @@ func (s *Signature) Scan(src interface{}) error {
 		return fmt.Errorf("can't scan []byte of len %d into Signature, want %d", len(srcB), 64)
 	}
 	buf := [64]byte{}
-	copy(buf[:], srcB[:])
+	copy(buf[:], srcB)
 	_, err := s.Decompress(buf)
 	return err
 }

babyjub/helpers.go

@@ -12,7 +12,7 @@ import (
 // the original blake from the SHA3 competition and not the new blake2 version.
 func Blake512(m []byte) []byte {
 	h := blake512.New()
-	_, err := h.Write(m[:])
+	_, err := h.Write(m)
 	if err != nil {
 		panic(err)
 	}