Add scanner/valuer interface to signature

babyjub/eddsa.go

@@ -2,6 +2,8 @@ package babyjub
 
 import (
 	"crypto/rand"
+	"database/sql/driver"
+	"fmt"
 
 	"github.com/iden3/go-iden3-crypto/mimc7"
 	"github.com/iden3/go-iden3-crypto/poseidon"
@@ -175,6 +177,27 @@ func (s *SignatureComp) Decompress() (*Signature, error) {
 	return new(Signature).Decompress(*s)
 }
 
+// Scan implements Scanner for database/sql.
+func (s *Signature) Scan(src interface{}) error {
+	srcB, ok := src.([]byte)
+	if !ok {
+		return fmt.Errorf("can't scan %T into Signature", src)
+	}
+	if len(srcB) != 64 {
+		return fmt.Errorf("can't scan []byte of len %d into Signature, want %d", len(srcB), 64)
+	}
+	buf := [64]byte{}
+	copy(buf[:], srcB[:])
+	_, err := s.Decompress(buf)
+	return err
+}
+
+// Value implements valuer for database/sql.
+func (s *Signature) Value() (driver.Value, error) {
+	comp := s.Compress()
+	return comp[:], nil
+}
+
 // SignMimc7 signs a message encoded as a big.Int in Zq using blake-512 hash
 // for buffer hashing and mimc7 for big.Int hashing.
 func (k *PrivateKey) SignMimc7(msg *big.Int) *Signature {

babyjub/eddsa_test.go

@@ -6,6 +6,9 @@ import (
 	"math/big"
 	"testing"
 
+	"database/sql"
+	"database/sql/driver"
+
 	"github.com/iden3/go-iden3-crypto/constants"
 	"github.com/iden3/go-iden3-crypto/utils"
 	"github.com/stretchr/testify/assert"
@@ -132,6 +135,18 @@ func TestCompressDecompress(t *testing.T) {
 	}
 }
 
+func TestScannerValuer(t *testing.T) {
+	privK := NewRandPrivKey()
+	var value driver.Valuer
+	var scan sql.Scanner
+	value = privK.SignPoseidon(big.NewInt(674238462))
+	scan = privK.SignPoseidon(big.NewInt(1))
+	fromDB, err := value.Value()
+	assert.NoError(t, err)
+	assert.NoError(t, scan.Scan(fromDB))
+	assert.Equal(t, value, scan)
+}
+
 func BenchmarkBabyjubEddsa(b *testing.B) {
 	var k PrivateKey
 	_, err := hex.Decode(k[:], []byte("0001020304050607080900010203040506070809000102030405060708090001"))