/usr/lib/python2.7/dist-packages/google/auth/crypt/_python_rsa.py is in python-google-auth 1.3.0-2.
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#
# 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
import io
import json
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()
_JSON_FILE_PRIVATE_KEY = 'private_key'
_JSON_FILE_PRIVATE_KEY_ID = 'private_key_id'
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):
"""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)
@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)
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