Added delete option to database storage.

venv/Lib/site-packages/google/auth/crypt/__init__.py

@@ -0,0 +1,100 @@
+# Copyright 2016 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Cryptography helpers for verifying and signing messages.
+
+The simplest way to verify signatures is using :func:`verify_signature`::
+
+    cert = open('certs.pem').read()
+    valid = crypt.verify_signature(message, signature, cert)
+
+If you're going to verify many messages with the same certificate, you can use
+:class:`RSAVerifier`::
+
+    cert = open('certs.pem').read()
+    verifier = crypt.RSAVerifier.from_string(cert)
+    valid = verifier.verify(message, signature)
+
+To sign messages use :class:`RSASigner` with a private key::
+
+    private_key = open('private_key.pem').read()
+    signer = crypt.RSASigner.from_string(private_key)
+    signature = signer.sign(message)
+
+The code above also works for :class:`ES256Signer` and :class:`ES256Verifier`.
+Note that these two classes are only available if your `cryptography` dependency
+version is at least 1.4.0.
+"""
+
+import six
+
+from google.auth.crypt import base
+from google.auth.crypt import rsa
+
+try:
+    from google.auth.crypt import es256
+except ImportError:  # pragma: NO COVER
+    es256 = None
+
+if es256 is not None:  # pragma: NO COVER
+    __all__ = [
+        "ES256Signer",
+        "ES256Verifier",
+        "RSASigner",
+        "RSAVerifier",
+        "Signer",
+        "Verifier",
+    ]
+else:  # pragma: NO COVER
+    __all__ = ["RSASigner", "RSAVerifier", "Signer", "Verifier"]
+
+
+# Aliases to maintain the v1.0.0 interface, as the crypt module was split
+# into submodules.
+Signer = base.Signer
+Verifier = base.Verifier
+RSASigner = rsa.RSASigner
+RSAVerifier = rsa.RSAVerifier
+
+if es256 is not None:  # pragma: NO COVER
+    ES256Signer = es256.ES256Signer
+    ES256Verifier = es256.ES256Verifier
+
+
+def verify_signature(message, signature, certs, verifier_cls=rsa.RSAVerifier):
+    """Verify an RSA or ECDSA cryptographic signature.
+
+    Checks that the provided ``signature`` was generated from ``bytes`` using
+    the private key associated with the ``cert``.
+
+    Args:
+        message (Union[str, bytes]): The plaintext message.
+        signature (Union[str, bytes]): The cryptographic signature to check.
+        certs (Union[Sequence, str, bytes]): The certificate or certificates
+            to use to check the signature.
+        verifier_cls (Optional[~google.auth.crypt.base.Signer]): Which verifier
+            class to use for verification. This can be used to select different
+            algorithms, such as RSA or ECDSA. Default value is :class:`RSAVerifier`.
+
+    Returns:
+        bool: True if the signature is valid, otherwise False.
+    """
+    if isinstance(certs, (six.text_type, six.binary_type)):
+        certs = [certs]
+
+    for cert in certs:
+        verifier = verifier_cls.from_string(cert)
+        if verifier.verify(message, signature):
+            return True
+    return False

venv/Lib/site-packages/google/auth/crypt/_cryptography_rsa.py

@@ -0,0 +1,149 @@
+# Copyright 2017 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""RSA verifier and signer that use the ``cryptography`` library.
+
+This is a much faster implementation than the default (in
+``google.auth.crypt._python_rsa``), which depends on the pure-Python
+``rsa`` library.
+"""
+
+import cryptography.exceptions
+from cryptography.hazmat import backends
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import padding
+import cryptography.x509
+import pkg_resources
+
+from google.auth import _helpers
+from google.auth.crypt import base
+
+_IMPORT_ERROR_MSG = (
+    "cryptography>=1.4.0 is required to use cryptography-based RSA " "implementation."
+)
+
+try:  # pragma: NO COVER
+    release = pkg_resources.get_distribution("cryptography").parsed_version
+    if release < pkg_resources.parse_version("1.4.0"):
+        raise ImportError(_IMPORT_ERROR_MSG)
+except pkg_resources.DistributionNotFound:  # pragma: NO COVER
+    raise ImportError(_IMPORT_ERROR_MSG)
+
+
+_CERTIFICATE_MARKER = b"-----BEGIN CERTIFICATE-----"
+_BACKEND = backends.default_backend()
+_PADDING = padding.PKCS1v15()
+_SHA256 = hashes.SHA256()
+
+
+class RSAVerifier(base.Verifier):
+    """Verifies RSA cryptographic signatures using public keys.
+
+    Args:
+        public_key (
+                cryptography.hazmat.primitives.asymmetric.rsa.RSAPublicKey):
+            The public key used to verify signatures.
+    """
+
+    def __init__(self, public_key):
+        self._pubkey = public_key
+
+    @_helpers.copy_docstring(base.Verifier)
+    def verify(self, message, signature):
+        message = _helpers.to_bytes(message)
+        try:
+            self._pubkey.verify(signature, message, _PADDING, _SHA256)
+            return True
+        except (ValueError, cryptography.exceptions.InvalidSignature):
+            return False
+
+    @classmethod
+    def from_string(cls, public_key):
+        """Construct an Verifier instance from a public key or public
+        certificate string.
+
+        Args:
+            public_key (Union[str, bytes]): The public key in PEM format or the
+                x509 public key certificate.
+
+        Returns:
+            Verifier: The constructed verifier.
+
+        Raises:
+            ValueError: If the public key can't be parsed.
+        """
+        public_key_data = _helpers.to_bytes(public_key)
+
+        if _CERTIFICATE_MARKER in public_key_data:
+            cert = cryptography.x509.load_pem_x509_certificate(
+                public_key_data, _BACKEND
+            )
+            pubkey = cert.public_key()
+
+        else:
+            pubkey = serialization.load_pem_public_key(public_key_data, _BACKEND)
+
+        return cls(pubkey)
+
+
+class RSASigner(base.Signer, base.FromServiceAccountMixin):
+    """Signs messages with an RSA private key.
+
+    Args:
+        private_key (
+                cryptography.hazmat.primitives.asymmetric.rsa.RSAPrivateKey):
+            The private key to sign with.
+        key_id (str): Optional key ID used to identify this private key. This
+            can be useful to associate the private key with its associated
+            public key or certificate.
+    """
+
+    def __init__(self, private_key, key_id=None):
+        self._key = private_key
+        self._key_id = key_id
+
+    @property
+    @_helpers.copy_docstring(base.Signer)
+    def key_id(self):
+        return self._key_id
+
+    @_helpers.copy_docstring(base.Signer)
+    def sign(self, message):
+        message = _helpers.to_bytes(message)
+        return self._key.sign(message, _PADDING, _SHA256)
+
+    @classmethod
+    def from_string(cls, key, key_id=None):
+        """Construct a RSASigner from a private key in PEM format.
+
+        Args:
+            key (Union[bytes, str]): Private key in PEM format.
+            key_id (str): An optional key id used to identify the private key.
+
+        Returns:
+            google.auth.crypt._cryptography_rsa.RSASigner: The
+            constructed signer.
+
+        Raises:
+            ValueError: If ``key`` is not ``bytes`` or ``str`` (unicode).
+            UnicodeDecodeError: If ``key`` is ``bytes`` but cannot be decoded
+                into a UTF-8 ``str``.
+            ValueError: If ``cryptography`` "Could not deserialize key data."
+        """
+        key = _helpers.to_bytes(key)
+        private_key = serialization.load_pem_private_key(
+            key, password=None, backend=_BACKEND
+        )
+        return cls(private_key, key_id=key_id)

venv/Lib/site-packages/google/auth/crypt/_python_rsa.py

@@ -0,0 +1,173 @@
+# Copyright 2016 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Pure-Python RSA cryptography implementation.
+
+Uses the ``rsa``, ``pyasn1`` and ``pyasn1_modules`` packages
+to parse PEM files storing PKCS#1 or PKCS#8 keys as well as
+certificates. There is no support for p12 files.
+"""
+
+from __future__ import absolute_import
+
+from pyasn1.codec.der import decoder
+from pyasn1_modules import pem
+from pyasn1_modules.rfc2459 import Certificate
+from pyasn1_modules.rfc5208 import PrivateKeyInfo
+import rsa
+import six
+
+from google.auth import _helpers
+from google.auth.crypt import base
+
+_POW2 = (128, 64, 32, 16, 8, 4, 2, 1)
+_CERTIFICATE_MARKER = b"-----BEGIN CERTIFICATE-----"
+_PKCS1_MARKER = ("-----BEGIN RSA PRIVATE KEY-----", "-----END RSA PRIVATE KEY-----")
+_PKCS8_MARKER = ("-----BEGIN PRIVATE KEY-----", "-----END PRIVATE KEY-----")
+_PKCS8_SPEC = PrivateKeyInfo()
+
+
+def _bit_list_to_bytes(bit_list):
+    """Converts an iterable of 1s and 0s to bytes.
+
+    Combines the list 8 at a time, treating each group of 8 bits
+    as a single byte.
+
+    Args:
+        bit_list (Sequence): Sequence of 1s and 0s.
+
+    Returns:
+        bytes: The decoded bytes.
+    """
+    num_bits = len(bit_list)
+    byte_vals = bytearray()
+    for start in six.moves.xrange(0, num_bits, 8):
+        curr_bits = bit_list[start : start + 8]
+        char_val = sum(val * digit for val, digit in six.moves.zip(_POW2, curr_bits))
+        byte_vals.append(char_val)
+    return bytes(byte_vals)
+
+
+class RSAVerifier(base.Verifier):
+    """Verifies RSA cryptographic signatures using public keys.
+
+    Args:
+        public_key (rsa.key.PublicKey): The public key used to verify
+            signatures.
+    """
+
+    def __init__(self, public_key):
+        self._pubkey = public_key
+
+    @_helpers.copy_docstring(base.Verifier)
+    def verify(self, message, signature):
+        message = _helpers.to_bytes(message)
+        try:
+            return rsa.pkcs1.verify(message, signature, self._pubkey)
+        except (ValueError, rsa.pkcs1.VerificationError):
+            return False
+
+    @classmethod
+    def from_string(cls, public_key):
+        """Construct an Verifier instance from a public key or public
+        certificate string.
+
+        Args:
+            public_key (Union[str, bytes]): The public key in PEM format or the
+                x509 public key certificate.
+
+        Returns:
+            Verifier: The constructed verifier.
+
+        Raises:
+            ValueError: If the public_key can't be parsed.
+        """
+        public_key = _helpers.to_bytes(public_key)
+        is_x509_cert = _CERTIFICATE_MARKER in public_key
+
+        # If this is a certificate, extract the public key info.
+        if is_x509_cert:
+            der = rsa.pem.load_pem(public_key, "CERTIFICATE")
+            asn1_cert, remaining = decoder.decode(der, asn1Spec=Certificate())
+            if remaining != b"":
+                raise ValueError("Unused bytes", remaining)
+
+            cert_info = asn1_cert["tbsCertificate"]["subjectPublicKeyInfo"]
+            key_bytes = _bit_list_to_bytes(cert_info["subjectPublicKey"])
+            pubkey = rsa.PublicKey.load_pkcs1(key_bytes, "DER")
+        else:
+            pubkey = rsa.PublicKey.load_pkcs1(public_key, "PEM")
+        return cls(pubkey)
+
+
+class RSASigner(base.Signer, base.FromServiceAccountMixin):
+    """Signs messages with an RSA private key.
+
+    Args:
+        private_key (rsa.key.PrivateKey): The private key to sign with.
+        key_id (str): Optional key ID used to identify this private key. This
+            can be useful to associate the private key with its associated
+            public key or certificate.
+    """
+
+    def __init__(self, private_key, key_id=None):
+        self._key = private_key
+        self._key_id = key_id
+
+    @property
+    @_helpers.copy_docstring(base.Signer)
+    def key_id(self):
+        return self._key_id
+
+    @_helpers.copy_docstring(base.Signer)
+    def sign(self, message):
+        message = _helpers.to_bytes(message)
+        return rsa.pkcs1.sign(message, self._key, "SHA-256")
+
+    @classmethod
+    def from_string(cls, key, key_id=None):
+        """Construct an Signer instance from a private key in PEM format.
+
+        Args:
+            key (str): Private key in PEM format.
+            key_id (str): An optional key id used to identify the private key.
+
+        Returns:
+            google.auth.crypt.Signer: The constructed signer.
+
+        Raises:
+            ValueError: If the key cannot be parsed as PKCS#1 or PKCS#8 in
+                PEM format.
+        """
+        key = _helpers.from_bytes(key)  # PEM expects str in Python 3
+        marker_id, key_bytes = pem.readPemBlocksFromFile(
+            six.StringIO(key), _PKCS1_MARKER, _PKCS8_MARKER
+        )
+
+        # Key is in pkcs1 format.
+        if marker_id == 0:
+            private_key = rsa.key.PrivateKey.load_pkcs1(key_bytes, format="DER")
+        # Key is in pkcs8.
+        elif marker_id == 1:
+            key_info, remaining = decoder.decode(key_bytes, asn1Spec=_PKCS8_SPEC)
+            if remaining != b"":
+                raise ValueError("Unused bytes", remaining)
+            private_key_info = key_info.getComponentByName("privateKey")
+            private_key = rsa.key.PrivateKey.load_pkcs1(
+                private_key_info.asOctets(), format="DER"
+            )
+        else:
+            raise ValueError("No key could be detected.")
+
+        return cls(private_key, key_id=key_id)

venv/Lib/site-packages/google/auth/crypt/base.py

@@ -0,0 +1,131 @@
+# Copyright 2016 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Base classes for cryptographic signers and verifiers."""
+
+import abc
+import io
+import json
+
+import six
+
+
+_JSON_FILE_PRIVATE_KEY = "private_key"
+_JSON_FILE_PRIVATE_KEY_ID = "private_key_id"
+
+
+@six.add_metaclass(abc.ABCMeta)
+class Verifier(object):
+    """Abstract base class for crytographic signature verifiers."""
+
+    @abc.abstractmethod
+    def verify(self, message, signature):
+        """Verifies a message against a cryptographic signature.
+
+        Args:
+            message (Union[str, bytes]): The message to verify.
+            signature (Union[str, bytes]): The cryptography signature to check.
+
+        Returns:
+            bool: True if message was signed by the private key associated
+            with the public key that this object was constructed with.
+        """
+        # pylint: disable=missing-raises-doc,redundant-returns-doc
+        # (pylint doesn't recognize that this is abstract)
+        raise NotImplementedError("Verify must be implemented")
+
+
+@six.add_metaclass(abc.ABCMeta)
+class Signer(object):
+    """Abstract base class for cryptographic signers."""
+
+    @abc.abstractproperty
+    def key_id(self):
+        """Optional[str]: The key ID used to identify this private key."""
+        raise NotImplementedError("Key id must be implemented")
+
+    @abc.abstractmethod
+    def sign(self, message):
+        """Signs a message.
+
+        Args:
+            message (Union[str, bytes]): The message to be signed.
+
+        Returns:
+            bytes: The signature of the message.
+        """
+        # pylint: disable=missing-raises-doc,redundant-returns-doc
+        # (pylint doesn't recognize that this is abstract)
+        raise NotImplementedError("Sign must be implemented")
+
+
+@six.add_metaclass(abc.ABCMeta)
+class FromServiceAccountMixin(object):
+    """Mix-in to enable factory constructors for a Signer."""
+
+    @abc.abstractmethod
+    def from_string(cls, key, key_id=None):
+        """Construct an Signer instance from a private key string.
+
+        Args:
+            key (str): Private key as a string.
+            key_id (str): An optional key id used to identify the private key.
+
+        Returns:
+            google.auth.crypt.Signer: The constructed signer.
+
+        Raises:
+            ValueError: If the key cannot be parsed.
+        """
+        raise NotImplementedError("from_string must be implemented")
+
+    @classmethod
+    def from_service_account_info(cls, info):
+        """Creates a Signer instance instance from a dictionary containing
+        service account info in Google format.
+
+        Args:
+            info (Mapping[str, str]): The service account info in Google
+                format.
+
+        Returns:
+            google.auth.crypt.Signer: The constructed signer.
+
+        Raises:
+            ValueError: If the info is not in the expected format.
+        """
+        if _JSON_FILE_PRIVATE_KEY not in info:
+            raise ValueError(
+                "The private_key field was not found in the service account " "info."
+            )
+
+        return cls.from_string(
+            info[_JSON_FILE_PRIVATE_KEY], info.get(_JSON_FILE_PRIVATE_KEY_ID)
+        )
+
+    @classmethod
+    def from_service_account_file(cls, filename):
+        """Creates a Signer instance from a service account .json file
+        in Google format.
+
+        Args:
+            filename (str): The path to the service account .json file.
+
+        Returns:
+            google.auth.crypt.Signer: The constructed signer.
+        """
+        with io.open(filename, "r", encoding="utf-8") as json_file:
+            data = json.load(json_file)
+
+        return cls.from_service_account_info(data)

venv/Lib/site-packages/google/auth/crypt/es256.py

@@ -0,0 +1,160 @@
+# Copyright 2017 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""ECDSA (ES256) verifier and signer that use the ``cryptography`` library.
+"""
+
+from cryptography import utils
+import cryptography.exceptions
+from cryptography.hazmat import backends
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import ec
+from cryptography.hazmat.primitives.asymmetric import padding
+from cryptography.hazmat.primitives.asymmetric.utils import decode_dss_signature
+from cryptography.hazmat.primitives.asymmetric.utils import encode_dss_signature
+import cryptography.x509
+import pkg_resources
+
+from google.auth import _helpers
+from google.auth.crypt import base
+
+_IMPORT_ERROR_MSG = (
+    "cryptography>=1.4.0 is required to use cryptography-based ECDSA " "algorithms"
+)
+
+try:  # pragma: NO COVER
+    release = pkg_resources.get_distribution("cryptography").parsed_version
+    if release < pkg_resources.parse_version("1.4.0"):
+        raise ImportError(_IMPORT_ERROR_MSG)
+except pkg_resources.DistributionNotFound:  # pragma: NO COVER
+    raise ImportError(_IMPORT_ERROR_MSG)
+
+
+_CERTIFICATE_MARKER = b"-----BEGIN CERTIFICATE-----"
+_BACKEND = backends.default_backend()
+_PADDING = padding.PKCS1v15()
+
+
+class ES256Verifier(base.Verifier):
+    """Verifies ECDSA cryptographic signatures using public keys.
+
+    Args:
+        public_key (
+                cryptography.hazmat.primitives.asymmetric.ec.ECDSAPublicKey):
+            The public key used to verify signatures.
+    """
+
+    def __init__(self, public_key):
+        self._pubkey = public_key
+
+    @_helpers.copy_docstring(base.Verifier)
+    def verify(self, message, signature):
+        # First convert (r||s) raw signature to ASN1 encoded signature.
+        sig_bytes = _helpers.to_bytes(signature)
+        if len(sig_bytes) != 64:
+            return False
+        r = utils.int_from_bytes(sig_bytes[:32], byteorder="big")
+        s = utils.int_from_bytes(sig_bytes[32:], byteorder="big")
+        asn1_sig = encode_dss_signature(r, s)
+
+        message = _helpers.to_bytes(message)
+        try:
+            self._pubkey.verify(asn1_sig, message, ec.ECDSA(hashes.SHA256()))
+            return True
+        except (ValueError, cryptography.exceptions.InvalidSignature):
+            return False
+
+    @classmethod
+    def from_string(cls, public_key):
+        """Construct an Verifier instance from a public key or public
+        certificate string.
+
+        Args:
+            public_key (Union[str, bytes]): The public key in PEM format or the
+                x509 public key certificate.
+
+        Returns:
+            Verifier: The constructed verifier.
+
+        Raises:
+            ValueError: If the public key can't be parsed.
+        """
+        public_key_data = _helpers.to_bytes(public_key)
+
+        if _CERTIFICATE_MARKER in public_key_data:
+            cert = cryptography.x509.load_pem_x509_certificate(
+                public_key_data, _BACKEND
+            )
+            pubkey = cert.public_key()
+
+        else:
+            pubkey = serialization.load_pem_public_key(public_key_data, _BACKEND)
+
+        return cls(pubkey)
+
+
+class ES256Signer(base.Signer, base.FromServiceAccountMixin):
+    """Signs messages with an ECDSA private key.
+
+    Args:
+        private_key (
+                cryptography.hazmat.primitives.asymmetric.ec.ECDSAPrivateKey):
+            The private key to sign with.
+        key_id (str): Optional key ID used to identify this private key. This
+            can be useful to associate the private key with its associated
+            public key or certificate.
+    """
+
+    def __init__(self, private_key, key_id=None):
+        self._key = private_key
+        self._key_id = key_id
+
+    @property
+    @_helpers.copy_docstring(base.Signer)
+    def key_id(self):
+        return self._key_id
+
+    @_helpers.copy_docstring(base.Signer)
+    def sign(self, message):
+        message = _helpers.to_bytes(message)
+        asn1_signature = self._key.sign(message, ec.ECDSA(hashes.SHA256()))
+
+        # Convert ASN1 encoded signature to (r||s) raw signature.
+        (r, s) = decode_dss_signature(asn1_signature)
+        return utils.int_to_bytes(r, 32) + utils.int_to_bytes(s, 32)
+
+    @classmethod
+    def from_string(cls, key, key_id=None):
+        """Construct a RSASigner from a private key in PEM format.
+
+        Args:
+            key (Union[bytes, str]): Private key in PEM format.
+            key_id (str): An optional key id used to identify the private key.
+
+        Returns:
+            google.auth.crypt._cryptography_rsa.RSASigner: The
+            constructed signer.
+
+        Raises:
+            ValueError: If ``key`` is not ``bytes`` or ``str`` (unicode).
+            UnicodeDecodeError: If ``key`` is ``bytes`` but cannot be decoded
+                into a UTF-8 ``str``.
+            ValueError: If ``cryptography`` "Could not deserialize key data."
+        """
+        key = _helpers.to_bytes(key)
+        private_key = serialization.load_pem_private_key(
+            key, password=None, backend=_BACKEND
+        )
+        return cls(private_key, key_id=key_id)

venv/Lib/site-packages/google/auth/crypt/rsa.py

@@ -0,0 +1,30 @@
+# Copyright 2017 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""RSA cryptography signer and verifier."""
+
+
+try:
+    # Prefer cryptograph-based RSA implementation.
+    from google.auth.crypt import _cryptography_rsa
+
+    RSASigner = _cryptography_rsa.RSASigner
+    RSAVerifier = _cryptography_rsa.RSAVerifier
+except ImportError:  # pragma: NO COVER
+    # Fallback to pure-python RSA implementation if cryptography is
+    # unavailable.
+    from google.auth.crypt import _python_rsa
+
+    RSASigner = _python_rsa.RSASigner
+    RSAVerifier = _python_rsa.RSAVerifier