Beispiel #1
0
// VerifySignatureV3 returns nil iff sig is a valid signature, made by this
// public key, of the data hashed into signed. signed is mutated by this call.
func (pk *PublicKeyV3) VerifySignatureV3(signed hash.Hash, sig *SignatureV3) (err error) {
	if !pk.CanSign() {
		return errors.InvalidArgumentError("public key cannot generate signatures")
	}

	suffix := make([]byte, 5)
	suffix[0] = byte(sig.SigType)
	binary.BigEndian.PutUint32(suffix[1:], uint32(sig.CreationTime.Unix()))
	signed.Write(suffix)
	hashBytes := signed.Sum(nil)

	if hashBytes[0] != sig.HashTag[0] || hashBytes[1] != sig.HashTag[1] {
		return errors.SignatureError("hash tag doesn't match")
	}

	if pk.PubKeyAlgo != sig.PubKeyAlgo {
		return errors.InvalidArgumentError("public key and signature use different algorithms")
	}

	switch pk.PubKeyAlgo {
	case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly:
		if err = rsa.VerifyPKCS1v15(pk.PublicKey, sig.Hash, hashBytes, sig.RSASignature.bytes); err != nil {
			return errors.SignatureError("RSA verification failure")
		}
		return
	default:
		// V3 public keys only support RSA.
		panic("shouldn't happen")
	}
	panic("unreachable")
}
Beispiel #2
0
// VerifySignature returns nil iff sig is a valid signature, made by this
// public key, of the data hashed into signed. signed is mutated by this call.
func (pk *PublicKey) VerifySignature(signed hash.Hash, sig *Signature) (err error) {
	if !pk.CanSign() {
		return errors.InvalidArgumentError("public key cannot generate signatures")
	}

	signed.Write(sig.HashSuffix)
	hashBytes := signed.Sum(nil)

	// NOTE(maxtaco) 2016-08-22
	//
	// We used to do this:
	//
	// if hashBytes[0] != sig.HashTag[0] || hashBytes[1] != sig.HashTag[1] {
	//	  return errors.SignatureError("hash tag doesn't match")
	// }
	//
	// But don't do anything in this case. Some GPGs generate bad
	// 2-byte hash prefixes, but GPG also doesn't seem to care on
	// import. See BrentMaxwell's key. I think it's safe to disable
	// this check!

	if pk.PubKeyAlgo != sig.PubKeyAlgo {
		return errors.InvalidArgumentError("public key and signature use different algorithms")
	}

	switch pk.PubKeyAlgo {
	case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly:
		rsaPublicKey, _ := pk.PublicKey.(*rsa.PublicKey)
		err = rsa.VerifyPKCS1v15(rsaPublicKey, sig.Hash, hashBytes, sig.RSASignature.bytes)
		if err != nil {
			return errors.SignatureError("RSA verification failure")
		}
		return nil
	case PubKeyAlgoDSA:
		dsaPublicKey, _ := pk.PublicKey.(*dsa.PublicKey)
		// Need to truncate hashBytes to match FIPS 186-3 section 4.6.
		subgroupSize := (dsaPublicKey.Q.BitLen() + 7) / 8
		if len(hashBytes) > subgroupSize {
			hashBytes = hashBytes[:subgroupSize]
		}
		if !dsa.Verify(dsaPublicKey, hashBytes, new(big.Int).SetBytes(sig.DSASigR.bytes), new(big.Int).SetBytes(sig.DSASigS.bytes)) {
			return errors.SignatureError("DSA verification failure")
		}
		return nil
	case PubKeyAlgoECDSA:
		ecdsaPublicKey := pk.PublicKey.(*ecdsa.PublicKey)
		if !ecdsa.Verify(ecdsaPublicKey, hashBytes, new(big.Int).SetBytes(sig.ECDSASigR.bytes), new(big.Int).SetBytes(sig.ECDSASigS.bytes)) {
			return errors.SignatureError("ECDSA verification failure")
		}
		return nil
	case PubKeyAlgoEdDSA:
		if !pk.edk.Verify(hashBytes, sig.EdDSASigR, sig.EdDSASigS) {
			return errors.SignatureError("EdDSA verification failure")
		}
		return nil
	default:
		return errors.SignatureError("Unsupported public key algorithm used in signature")
	}
	panic("unreachable")
}
Beispiel #3
0
// VerifySignature returns nil iff sig is a valid signature, made by this
// public key, of the data hashed into signed. signed is mutated by this call.
func (pk *PublicKey) VerifySignature(signed hash.Hash, sig *Signature) (err error) {
	if !pk.CanSign() {
		return errors.InvalidArgumentError("public key cannot generate signatures")
	}

	signed.Write(sig.HashSuffix)
	hashBytes := signed.Sum(nil)

	if hashBytes[0] != sig.HashTag[0] || hashBytes[1] != sig.HashTag[1] {
		return errors.SignatureError("hash tag doesn't match")
	}

	if pk.PubKeyAlgo != sig.PubKeyAlgo {
		return errors.InvalidArgumentError("public key and signature use different algorithms")
	}

	switch pk.PubKeyAlgo {
	case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly:
		rsaPublicKey, _ := pk.PublicKey.(*rsa.PublicKey)
		err = rsa.VerifyPKCS1v15(rsaPublicKey, sig.Hash, hashBytes, sig.RSASignature.bytes)
		if err != nil {
			return errors.SignatureError("RSA verification failure")
		}
		return nil
	case PubKeyAlgoDSA:
		dsaPublicKey, _ := pk.PublicKey.(*dsa.PublicKey)
		// Need to truncate hashBytes to match FIPS 186-3 section 4.6.
		subgroupSize := (dsaPublicKey.Q.BitLen() + 7) / 8
		if len(hashBytes) > subgroupSize {
			hashBytes = hashBytes[:subgroupSize]
		}
		if !dsa.Verify(dsaPublicKey, hashBytes, new(big.Int).SetBytes(sig.DSASigR.bytes), new(big.Int).SetBytes(sig.DSASigS.bytes)) {
			return errors.SignatureError("DSA verification failure")
		}
		return nil
	case PubKeyAlgoECDSA:
		ecdsaPublicKey := pk.PublicKey.(*ecdsa.PublicKey)
		if !ecdsa.Verify(ecdsaPublicKey, hashBytes, new(big.Int).SetBytes(sig.ECDSASigR.bytes), new(big.Int).SetBytes(sig.ECDSASigS.bytes)) {
			return errors.SignatureError("ECDSA verification failure")
		}
		return nil
	case PubKeyAlgoEdDSA:
		if !pk.edk.Verify(hashBytes, sig.EdDSASigR, sig.EdDSASigS) {
			return errors.SignatureError("EdDSA verification failure")
		}
		return nil
	default:
		return errors.SignatureError("Unsupported public key algorithm used in signature")
	}
	panic("unreachable")
}
Beispiel #4
0
// VerifySignatureV3 returns nil iff sig is a valid signature, made by this
// public key, of the data hashed into signed. signed is mutated by this call.
func (pk *PublicKey) VerifySignatureV3(signed hash.Hash, sig *SignatureV3) (err error) {
	if !pk.CanSign() {
		return errors.InvalidArgumentError("public key cannot generate signatures")
	}

	suffix := make([]byte, 5)
	suffix[0] = byte(sig.SigType)
	binary.BigEndian.PutUint32(suffix[1:], uint32(sig.CreationTime.Unix()))
	signed.Write(suffix)
	hashBytes := signed.Sum(nil)

	if hashBytes[0] != sig.HashTag[0] || hashBytes[1] != sig.HashTag[1] {
		return errors.SignatureError("hash tag doesn't match")
	}

	if pk.PubKeyAlgo != sig.PubKeyAlgo {
		return errors.InvalidArgumentError("public key and signature use different algorithms")
	}

	switch pk.PubKeyAlgo {
	case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly:
		rsaPublicKey := pk.PublicKey.(*rsa.PublicKey)
		if err = rsa.VerifyPKCS1v15(rsaPublicKey, sig.Hash, hashBytes, sig.RSASignature.bytes); err != nil {
			return errors.SignatureError("RSA verification failure")
		}
		return
	case PubKeyAlgoDSA:
		dsaPublicKey := pk.PublicKey.(*dsa.PublicKey)
		// Need to truncate hashBytes to match FIPS 186-3 section 4.6.
		subgroupSize := (dsaPublicKey.Q.BitLen() + 7) / 8
		if len(hashBytes) > subgroupSize {
			hashBytes = hashBytes[:subgroupSize]
		}
		if !dsa.Verify(dsaPublicKey, hashBytes, new(big.Int).SetBytes(sig.DSASigR.bytes), new(big.Int).SetBytes(sig.DSASigS.bytes)) {
			return errors.SignatureError("DSA verification failure")
		}
		return nil
	default:
		panic("shouldn't happen")
	}
	panic("unreachable")
}