codekingpro/portable-devtools

1# Copyright 2017 Google Inc.2#3# Licensed under the Apache License, Version 2.0 (the "License");4# you may not use this file except in compliance with the License.5# You may obtain a copy of the License at6#7#      http://www.apache.org/licenses/LICENSE-2.08#9# Unless required by applicable law or agreed to in writing, software10# distributed under the License is distributed on an "AS IS" BASIS,11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.12# See the License for the specific language governing permissions and13# limitations under the License.14 15"""ECDSA (ES256) verifier and signer that use the ``cryptography`` library.16"""17 18from cryptography import utils  # type: ignore19import cryptography.exceptions20from cryptography.hazmat import backends21from cryptography.hazmat.primitives import hashes22from cryptography.hazmat.primitives import serialization23from cryptography.hazmat.primitives.asymmetric import ec24from cryptography.hazmat.primitives.asymmetric import padding25from cryptography.hazmat.primitives.asymmetric.utils import decode_dss_signature26from cryptography.hazmat.primitives.asymmetric.utils import encode_dss_signature27import cryptography.x50928 29from google.auth import _helpers30from google.auth.crypt import base31 32 33_CERTIFICATE_MARKER = b"-----BEGIN CERTIFICATE-----"34_BACKEND = backends.default_backend()35_PADDING = padding.PKCS1v15()36 37 38class ES256Verifier(base.Verifier):39    """Verifies ECDSA cryptographic signatures using public keys.40 41    Args:42        public_key (43                cryptography.hazmat.primitives.asymmetric.ec.ECDSAPublicKey):44            The public key used to verify signatures.45    """46 47    def __init__(self, public_key):48        self._pubkey = public_key49 50    @_helpers.copy_docstring(base.Verifier)51    def verify(self, message, signature):52        # First convert (r||s) raw signature to ASN1 encoded signature.53        sig_bytes = _helpers.to_bytes(signature)54        if len(sig_bytes) != 64:55            return False56        r = (57            int.from_bytes(sig_bytes[:32], byteorder="big")58            if _helpers.is_python_3()59            else utils.int_from_bytes(sig_bytes[:32], byteorder="big")60        )61        s = (62            int.from_bytes(sig_bytes[32:], byteorder="big")63            if _helpers.is_python_3()64            else utils.int_from_bytes(sig_bytes[32:], byteorder="big")65        )66        asn1_sig = encode_dss_signature(r, s)67 68        message = _helpers.to_bytes(message)69        try:70            self._pubkey.verify(asn1_sig, message, ec.ECDSA(hashes.SHA256()))71            return True72        except (ValueError, cryptography.exceptions.InvalidSignature):73            return False74 75    @classmethod76    def from_string(cls, public_key):77        """Construct an Verifier instance from a public key or public78        certificate string.79 80        Args:81            public_key (Union[str, bytes]): The public key in PEM format or the82                x509 public key certificate.83 84        Returns:85            Verifier: The constructed verifier.86 87        Raises:88            ValueError: If the public key can't be parsed.89        """90        public_key_data = _helpers.to_bytes(public_key)91 92        if _CERTIFICATE_MARKER in public_key_data:93            cert = cryptography.x509.load_pem_x509_certificate(94                public_key_data, _BACKEND95            )96            pubkey = cert.public_key()97 98        else:99            pubkey = serialization.load_pem_public_key(public_key_data, _BACKEND)100 101        return cls(pubkey)102 103 104class ES256Signer(base.Signer, base.FromServiceAccountMixin):105    """Signs messages with an ECDSA private key.106 107    Args:108        private_key (109                cryptography.hazmat.primitives.asymmetric.ec.ECDSAPrivateKey):110            The private key to sign with.111        key_id (str): Optional key ID used to identify this private key. This112            can be useful to associate the private key with its associated113            public key or certificate.114    """115 116    def __init__(self, private_key, key_id=None):117        self._key = private_key118        self._key_id = key_id119 120    @property  # type: ignore121    @_helpers.copy_docstring(base.Signer)122    def key_id(self):123        return self._key_id124 125    @_helpers.copy_docstring(base.Signer)126    def sign(self, message):127        message = _helpers.to_bytes(message)128        asn1_signature = self._key.sign(message, ec.ECDSA(hashes.SHA256()))129 130        # Convert ASN1 encoded signature to (r||s) raw signature.131        (r, s) = decode_dss_signature(asn1_signature)132        return (133            (r.to_bytes(32, byteorder="big") + s.to_bytes(32, byteorder="big"))134            if _helpers.is_python_3()135            else (utils.int_to_bytes(r, 32) + utils.int_to_bytes(s, 32))136        )137 138    @classmethod139    def from_string(cls, key, key_id=None):140        """Construct a RSASigner from a private key in PEM format.141 142        Args:143            key (Union[bytes, str]): Private key in PEM format.144            key_id (str): An optional key id used to identify the private key.145 146        Returns:147            google.auth.crypt._cryptography_rsa.RSASigner: The148            constructed signer.149 150        Raises:151            ValueError: If ``key`` is not ``bytes`` or ``str`` (unicode).152            UnicodeDecodeError: If ``key`` is ``bytes`` but cannot be decoded153                into a UTF-8 ``str``.154            ValueError: If ``cryptography`` "Could not deserialize key data."155        """156        key = _helpers.to_bytes(key)157        private_key = serialization.load_pem_private_key(158            key, password=None, backend=_BACKEND159        )160        return cls(private_key, key_id=key_id)161 162    def __getstate__(self):163        """Pickle helper that serializes the _key attribute."""164        state = self.__dict__.copy()165        state["_key"] = self._key.private_bytes(166            encoding=serialization.Encoding.PEM,167            format=serialization.PrivateFormat.PKCS8,168            encryption_algorithm=serialization.NoEncryption(),169        )170        return state171 172    def __setstate__(self, state):173        """Pickle helper that deserializes the _key attribute."""174        state["_key"] = serialization.load_pem_private_key(state["_key"], None)175        self.__dict__.update(state)176