Beispiel #1
0
// Verify returns true iff sig is a valid signature of message by publicKey.
func Verify(publicKey *[PublicKeySize]byte, message []byte, sig *[SignatureSize]byte) bool {
	if sig[63]&224 != 0 {
		return false
	}

	var A edwards25519.ExtendedGroupElement
	if !A.FromBytes(publicKey) {
		return false
	}
	edwards25519.FeNeg(&A.X, &A.X)
	edwards25519.FeNeg(&A.T, &A.T)

	h := sha512.New()
	h.Write(sig[:32])
	h.Write(publicKey[:])
	h.Write(message)
	var digest [64]byte
	h.Sum(digest[:0])

	var hReduced [32]byte
	edwards25519.ScReduce(&hReduced, &digest)

	var R edwards25519.ProjectiveGroupElement
	var b [32]byte
	copy(b[:], sig[32:])
	edwards25519.GeDoubleScalarMultVartime(&R, &hReduced, &A, &b)

	var checkR [32]byte
	R.ToBytes(&checkR)
	return subtle.ConstantTimeCompare(sig[:32], checkR[:]) == 1
}
Beispiel #2
0
// PublicKeyToCurve25519 converts an Ed25519 public key into the curve25519
// public key that would be generated from the same private key.
func PublicKeyToCurve25519(curve25519Public *[32]byte, publicKey *[32]byte) bool {
	var A edwards25519.ExtendedGroupElement
	if !A.FromBytes(publicKey) {
		return false
	}

	// A.Z = 1 as a postcondition of FromBytes.
	var x edwards25519.FieldElement
	edwardsToMontgomeryX(&x, &A.Y)
	edwards25519.FeToBytes(curve25519Public, &x)
	return true
}
Beispiel #3
0
func TestUnmarshalMarshalNegative(t *testing.T) {
	pk, _, _ := GenerateKey(rand.Reader)

	var A edwards25519.ExtendedGroupElement
	ret := A.FromBytes(pk)

	var pk2 [32]byte
	A.ToBytes(&pk2)
	pk2[31] ^= 0x80

	if *pk == pk2 {
		t.Errorf("flipping sign did not change public key:\n%x\nbytes:\n\t%x\n\t%x\ndelta: %x\n", ret, A, *pk, pk2, int(pk[31])-int(pk2[31]))
	}
}
Beispiel #4
0
func TestUnmarshalMarshal(t *testing.T) {
	pk, _, _ := GenerateKey(rand.Reader)

	var A edwards25519.ExtendedGroupElement
	ret := A.FromBytes(pk)

	var pk2 [32]byte
	A.ToBytes(&pk2)

	if *pk != pk2 {
		_ = ret
		t.Errorf("FromBytes(%v)->ToBytes not idempotent:\n%x\nbytes:\n\t%x\n\t%x\ndelta: %x\n", ret, A, *pk, pk2, int(pk[31])-int(pk2[31]))
	}
}
Beispiel #5
0
func TestUnmarshalMarshal(t *testing.T) {
	pub, _, _ := GenerateKey(rand.Reader)

	var A edwards25519.ExtendedGroupElement
	if !A.FromBytes(pub) {
		t.Fatalf("ExtendedGroupElement.FromBytes failed")
	}

	var pub2 [32]byte
	A.ToBytes(&pub2)

	if *pub != pub2 {
		t.Errorf("FromBytes(%v)->ToBytes does not round-trip, got %x\n", *pub, pub2)
	}
}