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