Source code for google.auth.crypt.base

# 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"


[docs]@six.add_metaclass(abc.ABCMeta) class Verifier(object): """Abstract base class for crytographic signature verifiers."""
[docs] @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")
[docs]@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")
[docs] @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")
[docs]@six.add_metaclass(abc.ABCMeta) class FromServiceAccountMixin(object): """Mix-in to enable factory constructors for a Signer."""
[docs] @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")
[docs] @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) )
[docs] @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)