support hash interface for poseidon; support golang crypto interfaces for bjj

babyjub/babyjub_wrapper.go

@@ -0,0 +1,81 @@
+package babyjub
+
+import (
+	"bytes"
+	"crypto"
+	"io"
+	"math/big"
+)
+
+// BjjWrappedPublicKey is a wrapper for PublicKey.
+type BjjWrappedPublicKey struct {
+	pubKey *PublicKey
+}
+
+// Equal returns true if the public keys are equal.
+func (pub *BjjWrappedPublicKey) Equal(x crypto.PublicKey) bool {
+	var xk *BjjWrappedPublicKey
+	switch x := x.(type) {
+	case BjjWrappedPublicKey:
+		xk = &x
+	case *BjjWrappedPublicKey:
+		xk = x
+	default:
+		return false
+	}
+	return pub.pubKey.X.Cmp(xk.pubKey.X) == 0 &&
+		pub.pubKey.Y.Cmp(xk.pubKey.Y) == 0
+}
+
+// BjjWrappedPrivateKey is a wrapper for PrivateKey.
+type BjjWrappedPrivateKey struct {
+	privKey *PrivateKey
+}
+
+// NewBjjWrappedKey creates a new BjjWrappedPrivateKey.
+func NewBjjWrappedKey(privKey *PrivateKey) *BjjWrappedPrivateKey {
+	return &BjjWrappedPrivateKey{privKey}
+}
+
+// RandomBjjWrappedKey creates a new BjjWrappedPrivateKey with a random private key.
+func RandomBjjWrappedKey() *BjjWrappedPrivateKey {
+	privKey := NewRandPrivKey()
+	return NewBjjWrappedKey(&privKey)
+}
+
+// Public returns the public key of the private key.
+func (w *BjjWrappedPrivateKey) Public() crypto.PublicKey {
+	return &BjjWrappedPublicKey{w.privKey.Public()}
+}
+
+// Sign signs the digest with the private key.
+func (w *BjjWrappedPrivateKey) Sign(rand io.Reader, digest []byte, opts crypto.SignerOpts) ([]byte, error) {
+	hash := opts.HashFunc()
+
+	switch hash {
+	// alredy hashed
+	case crypto.Hash(0):
+	default:
+		hasher := hash.New()
+		hasher.Write(digest)
+		digest = hasher.Sum(nil)
+	}
+
+	digestBI := big.NewInt(0).SetBytes(digest)
+	sig := w.privKey.SignPoseidon(digestBI)
+	return sig.Compress().MarshalText()
+}
+
+// Equal returns true if the private keys are equal.
+func (w *BjjWrappedPrivateKey) Equal(x crypto.PrivateKey) bool {
+	var xk *BjjWrappedPrivateKey
+	switch x := x.(type) {
+	case BjjWrappedPrivateKey:
+		xk = &x
+	case *BjjWrappedPrivateKey:
+		xk = x
+	default:
+		return false
+	}
+	return bytes.Equal(w.privKey[:], xk.privKey[:])
+}

babyjub/babyjub_wrapper_test.go

@@ -0,0 +1,76 @@
+package babyjub
+
+import (
+	"crypto"
+	"crypto/rand"
+	"math/big"
+	"testing"
+
+	"github.com/iden3/go-iden3-crypto/poseidon"
+	"github.com/stretchr/testify/require"
+)
+
+// https://pkg.go.dev/crypto#PrivateKey
+type shadowPrivateKey interface {
+	Public() crypto.PublicKey
+	Equal(x crypto.PrivateKey) bool
+}
+
+// https://pkg.go.dev/crypto#PublicKey
+type shadowPublicKey interface {
+	Equal(x crypto.PublicKey) bool
+}
+
+func TestBjjWrappedPrivateKeyInterfaceImpl(t *testing.T) {
+	require.Implements(t, (*crypto.Signer)(nil), new(BjjWrappedPrivateKey))
+	require.Implements(t, (*shadowPrivateKey)(nil), new(BjjWrappedPrivateKey))
+}
+
+func TestBjjWrappedPrivateKey(t *testing.T) {
+	pk := RandomBjjWrappedKey()
+
+	hasher := poseidon.New()
+	hasher.Write([]byte("test"))
+	digest := hasher.Sum(nil)
+
+	sig, err := pk.Sign(rand.Reader, digest, crypto.Hash(0))
+	require.NoError(t, err)
+	pub, ok := pk.Public().(*BjjWrappedPublicKey)
+	require.True(t, ok)
+
+	decomrpessSig, err := decomrpessSig(sig)
+	require.NoError(t, err)
+
+	digestBI := big.NewInt(0).SetBytes(digest)
+	pub.pubKey.VerifyPoseidon(digestBI, decomrpessSig)
+}
+
+func TestBjjWrappedPrivateKeyEqual(t *testing.T) {
+	x1 := RandomBjjWrappedKey()
+	require.True(t, x1.Equal(x1))
+	x2 := RandomBjjWrappedKey()
+	require.False(t, x1.Equal(x2))
+}
+
+func TestBjjWrappedPublicKeyInterfaceImpl(t *testing.T) {
+	require.Implements(t, (*shadowPublicKey)(nil), new(BjjWrappedPublicKey))
+}
+
+func TestBjjWrappedPublicKeyEqual(t *testing.T) {
+	x1 := RandomBjjWrappedKey().Public().(*BjjWrappedPublicKey)
+	require.True(t, x1.Equal(x1))
+	x2 := RandomBjjWrappedKey().Public()
+	require.False(t, x1.Equal(x2))
+}
+
+func decomrpessSig(commpresedSig []byte) (*Signature, error) {
+	poseidonComSig := &SignatureComp{}
+	if err := poseidonComSig.UnmarshalText(commpresedSig); err != nil {
+		return nil, err
+	}
+	poseidonDecSig, err := poseidonComSig.Decompress()
+	if err != nil {
+		return nil, err
+	}
+	return poseidonDecSig, nil
+}