codekingpro/portable-devtools

1# Copyright 2016 Google LLC2#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"""Pure-Python RSA cryptography implementation.16 17Uses the ``rsa``, ``pyasn1`` and ``pyasn1_modules`` packages18to parse PEM files storing PKCS#1 or PKCS#8 keys as well as19certificates. There is no support for p12 files.20"""21 22from __future__ import absolute_import23 24import io25 26from pyasn1.codec.der import decoder  # type: ignore27from pyasn1_modules import pem  # type: ignore28from pyasn1_modules.rfc2459 import Certificate  # type: ignore29from pyasn1_modules.rfc5208 import PrivateKeyInfo  # type: ignore30import rsa  # type: ignore31 32from google.auth import _helpers33from google.auth import exceptions34from google.auth.crypt import base35 36_POW2 = (128, 64, 32, 16, 8, 4, 2, 1)37_CERTIFICATE_MARKER = b"-----BEGIN CERTIFICATE-----"38_PKCS1_MARKER = ("-----BEGIN RSA PRIVATE KEY-----", "-----END RSA PRIVATE KEY-----")39_PKCS8_MARKER = ("-----BEGIN PRIVATE KEY-----", "-----END PRIVATE KEY-----")40_PKCS8_SPEC = PrivateKeyInfo()41 42 43def _bit_list_to_bytes(bit_list):44    """Converts an iterable of 1s and 0s to bytes.45 46    Combines the list 8 at a time, treating each group of 8 bits47    as a single byte.48 49    Args:50        bit_list (Sequence): Sequence of 1s and 0s.51 52    Returns:53        bytes: The decoded bytes.54    """55    num_bits = len(bit_list)56    byte_vals = bytearray()57    for start in range(0, num_bits, 8):58        curr_bits = bit_list[start : start + 8]59        char_val = sum(val * digit for val, digit in zip(_POW2, curr_bits))60        byte_vals.append(char_val)61    return bytes(byte_vals)62 63 64class RSAVerifier(base.Verifier):65    """Verifies RSA cryptographic signatures using public keys.66 67    Args:68        public_key (rsa.key.PublicKey): The public key used to verify69            signatures.70    """71 72    def __init__(self, public_key):73        self._pubkey = public_key74 75    @_helpers.copy_docstring(base.Verifier)76    def verify(self, message, signature):77        message = _helpers.to_bytes(message)78        try:79            return rsa.pkcs1.verify(message, signature, self._pubkey)80        except (ValueError, rsa.pkcs1.VerificationError):81            return False82 83    @classmethod84    def from_string(cls, public_key):85        """Construct an Verifier instance from a public key or public86        certificate string.87 88        Args:89            public_key (Union[str, bytes]): The public key in PEM format or the90                x509 public key certificate.91 92        Returns:93            google.auth.crypt._python_rsa.RSAVerifier: The constructed verifier.94 95        Raises:96            ValueError: If the public_key can't be parsed.97        """98        public_key = _helpers.to_bytes(public_key)99        is_x509_cert = _CERTIFICATE_MARKER in public_key100 101        # If this is a certificate, extract the public key info.102        if is_x509_cert:103            der = rsa.pem.load_pem(public_key, "CERTIFICATE")104            asn1_cert, remaining = decoder.decode(der, asn1Spec=Certificate())105            if remaining != b"":106                raise exceptions.InvalidValue("Unused bytes", remaining)107 108            cert_info = asn1_cert["tbsCertificate"]["subjectPublicKeyInfo"]109            key_bytes = _bit_list_to_bytes(cert_info["subjectPublicKey"])110            pubkey = rsa.PublicKey.load_pkcs1(key_bytes, "DER")111        else:112            pubkey = rsa.PublicKey.load_pkcs1(public_key, "PEM")113        return cls(pubkey)114 115 116class RSASigner(base.Signer, base.FromServiceAccountMixin):117    """Signs messages with an RSA private key.118 119    Args:120        private_key (rsa.key.PrivateKey): The private key to sign with.121        key_id (str): Optional key ID used to identify this private key. This122            can be useful to associate the private key with its associated123            public key or certificate.124    """125 126    def __init__(self, private_key, key_id=None):127        self._key = private_key128        self._key_id = key_id129 130    @property  # type: ignore131    @_helpers.copy_docstring(base.Signer)132    def key_id(self):133        return self._key_id134 135    @_helpers.copy_docstring(base.Signer)136    def sign(self, message):137        message = _helpers.to_bytes(message)138        return rsa.pkcs1.sign(message, self._key, "SHA-256")139 140    @classmethod141    def from_string(cls, key, key_id=None):142        """Construct an Signer instance from a private key in PEM format.143 144        Args:145            key (str): Private key in PEM format.146            key_id (str): An optional key id used to identify the private key.147 148        Returns:149            google.auth.crypt.Signer: The constructed signer.150 151        Raises:152            ValueError: If the key cannot be parsed as PKCS#1 or PKCS#8 in153                PEM format.154        """155        key = _helpers.from_bytes(key)  # PEM expects str in Python 3156        marker_id, key_bytes = pem.readPemBlocksFromFile(157            io.StringIO(key), _PKCS1_MARKER, _PKCS8_MARKER158        )159 160        # Key is in pkcs1 format.161        if marker_id == 0:162            private_key = rsa.key.PrivateKey.load_pkcs1(key_bytes, format="DER")163        # Key is in pkcs8.164        elif marker_id == 1:165            key_info, remaining = decoder.decode(key_bytes, asn1Spec=_PKCS8_SPEC)166            if remaining != b"":167                raise exceptions.InvalidValue("Unused bytes", remaining)168            private_key_info = key_info.getComponentByName("privateKey")169            private_key = rsa.key.PrivateKey.load_pkcs1(170                private_key_info.asOctets(), format="DER"171            )172        else:173            raise exceptions.MalformedError("No key could be detected.")174 175        return cls(private_key, key_id=key_id)176