Exemplo n.º 1
0
func NewEcdsaPublicKey(pk *ecdsa.PublicKey) *EcdsaPublicKey {
	pubkey := &EcdsaPublicKey{
		Curve: jwa.EllipticCurveAlgorithm(pk.Params().Name),
	}
	pubkey.X.SetBytes(pk.X.Bytes())
	pubkey.Y.SetBytes(pk.Y.Bytes())
	return pubkey
}
Exemplo n.º 2
0
// NewEcdsaPublicKey creates a new JWK from a EC-DSA public key
func NewEcdsaPublicKey(pk *ecdsa.PublicKey) *EcdsaPublicKey {
	pubkey := &EcdsaPublicKey{
		EssentialHeader: &EssentialHeader{KeyType: jwa.EC},
		Curve:           jwa.EllipticCurveAlgorithm(pk.Params().Name),
	}
	n := pk.Params().BitSize / 8
	pubkey.X.SetBytes(i2osp(pk.X, n))
	pubkey.Y.SetBytes(i2osp(pk.Y, n))
	return pubkey
}
Exemplo n.º 3
0
func (sv *x509ECDSASignatureVerifierImpl) verifyImpl(vk *ecdsa.PublicKey, signature, message []byte) (bool, error) {
	ecdsaSignature := new(ECDSASignature)
	_, err := asn1.Unmarshal(signature, ecdsaSignature)
	if err != nil {
		return false, err
	}

	h, err := computeHash(message, vk.Params().BitSize)
	if err != nil {
		return false, err
	}

	return ecdsa.Verify(vk, h, ecdsaSignature.R, ecdsaSignature.S), nil
}
Exemplo n.º 4
0
// marshalPubECDSA serializes an ECDSA public key according to RFC 5656, section 3.1.
func marshalPubECDSA(key *ecdsa.PublicKey) []byte {
	var identifier []byte
	switch key.Params().BitSize {
	case 256:
		identifier = []byte("nistp256")
	case 384:
		identifier = []byte("nistp384")
	case 521:
		identifier = []byte("nistp521")
	default:
		panic("ssh: unsupported ecdsa key size")
	}
	keyBytes := elliptic.Marshal(key.Curve, key.X, key.Y)

	length := stringLength(len(identifier))
	length += stringLength(len(keyBytes))

	ret := make([]byte, length)
	r := marshalString(ret, identifier)
	r = marshalString(r, keyBytes)
	return ret
}
Exemplo n.º 5
0
// GoodKeyECDSA determines if an ECDSA pubkey meets our requirements
func (policy *KeyPolicy) goodKeyECDSA(key ecdsa.PublicKey) (err error) {
	// Check the curve.
	//
	// The validity of the curve is an assumption for all following tests.
	err = policy.goodCurve(key.Curve)
	if err != nil {
		return err
	}

	// Key validation routine adapted from NIST SP800-56A § 5.6.2.3.2.
	// <http://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-56Ar2.pdf>
	//
	// Assuming a prime field since a) we are only allowing such curves and b)
	// crypto/elliptic only supports prime curves. Where this assumption
	// simplifies the code below, it is explicitly stated and explained. If ever
	// adapting this code to support non-prime curves, refer to NIST SP800-56A §
	// 5.6.2.3.2 and adapt this code appropriately.
	params := key.Params()

	// SP800-56A § 5.6.2.3.2 Step 1.
	// Partial check of the public key for an invalid range in the EC group:
	// Verify that key is not the point at infinity O.
	// This code assumes that the point at infinity is (0,0), which is the
	// case for all supported curves.
	if isPointAtInfinityNISTP(key.X, key.Y) {
		return core.MalformedRequestError("Key x, y must not be the point at infinity")
	}

	// SP800-56A § 5.6.2.3.2 Step 2.
	//   "Verify that x_Q and y_Q are integers in the interval [0,p-1] in the
	//    case that q is an odd prime p, or that x_Q and y_Q are bit strings
	//    of length m bits in the case that q = 2**m."
	//
	// Prove prime field: ASSUMED.
	// Prove q != 2: ASSUMED. (Curve parameter. No supported curve has q == 2.)
	// Prime field && q != 2  => q is an odd prime p
	// Therefore "verify that x, y are in [0, p-1]" satisfies step 2.
	//
	// Therefore verify that both x and y of the public key point have the unique
	// correct representation of an element in the underlying field by verifying
	// that x and y are integers in [0, p-1].
	if key.X.Sign() < 0 || key.Y.Sign() < 0 {
		return core.MalformedRequestError("Key x, y must not be negative")
	}

	if key.X.Cmp(params.P) >= 0 || key.Y.Cmp(params.P) >= 0 {
		return core.MalformedRequestError("Key x, y must not exceed P-1")
	}

	// SP800-56A § 5.6.2.3.2 Step 3.
	//   "If q is an odd prime p, verify that (y_Q)**2 === (x_Q)***3 + a*x_Q + b (mod p).
	//    If q = 2**m, verify that (y_Q)**2 + (x_Q)*(y_Q) == (x_Q)**3 + a*(x_Q)*2 + b in
	//    the finite field of size 2**m.
	//    (Ensures that the public key is on the correct elliptic curve.)"
	//
	// q is an odd prime p: proven/assumed above.
	// a = -3 for all supported curves.
	//
	// Therefore step 3 is satisfied simply by showing that
	//   y**2 === x**3 - 3*x + B (mod P).
	//
	// This proves that the public key is on the correct elliptic curve.
	// But in practice, this test is provided by crypto/elliptic, so use that.
	if !key.Curve.IsOnCurve(key.X, key.Y) {
		return core.MalformedRequestError("Key point is not on the curve")
	}

	// SP800-56A § 5.6.2.3.2 Step 4.
	//   "Verify that n*Q == O.
	//    (Ensures that the public key has the correct order. Along with check 1,
	//     ensures that the public key is in the correct range in the correct EC
	//     subgroup, that is, it is in the correct EC subgroup and is not the
	//     identity element.)"
	//
	// Ensure that public key has the correct order:
	// verify that n*Q = O.
	//
	// n*Q = O iff n*Q is the point at infinity (see step 1).
	ox, oy := key.Curve.ScalarMult(key.X, key.Y, params.N.Bytes())
	if !isPointAtInfinityNISTP(ox, oy) {
		return core.MalformedRequestError("Public key does not have correct order")
	}

	// End of SP800-56A § 5.6.2.3.2 Public Key Validation Routine.
	// Key is valid.
	return nil
}