prolin-xcb-client/adb/sign_pythonrsa.py

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2019-05-14 08:40:17 +02:00
# Copyright 2014 Google Inc. All rights reserved.
#
# 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.
import rsa
from pyasn1.codec.der import decoder
from pyasn1.type import univ
from rsa import pkcs1
# python-rsa lib hashes all messages it signs. ADB does it already, we just
# need to slap a signature on top of already hashed message. Introduce "fake"
# hashing algo for this.
class _Accum(object):
def __init__(self):
self._buf = b''
def update(self, msg):
self._buf += msg
def digest(self):
return self._buf
pkcs1.HASH_METHODS['SHA-1-PREHASHED'] = _Accum
pkcs1.HASH_ASN1['SHA-1-PREHASHED'] = pkcs1.HASH_ASN1['SHA-1']
def _load_rsa_private_key(pem):
"""PEM encoded PKCS#8 private key -> rsa.PrivateKey."""
# ADB uses private RSA keys in pkcs#8 format. 'rsa' library doesn't support
# them natively. Do some ASN unwrapping to extract naked RSA key
# (in der-encoded form). See https://www.ietf.org/rfc/rfc2313.txt.
# Also http://superuser.com/a/606266.
try:
der = rsa.pem.load_pem(pem, 'PRIVATE KEY')
keyinfo, _ = decoder.decode(der)
if keyinfo[1][0] != univ.ObjectIdentifier(
'1.2.840.113549.1.1.1'): # pragma: no cover
raise ValueError('Not a DER-encoded OpenSSL private RSA key')
private_key_der = keyinfo[2].asOctets()
except IndexError: # pragma: no cover
raise ValueError('Not a DER-encoded OpenSSL private RSA key')
return rsa.PrivateKey.load_pkcs1(private_key_der, format='DER')
class PythonRSASigner(object):
"""Implements adb_protocol.AuthSigner using http://stuvel.eu/rsa."""
@classmethod
def FromRSAKeyPath(cls, rsa_key_path):
with open(rsa_key_path + '.pub') as f:
pub = f.read()
with open(rsa_key_path) as f:
priv = f.read()
return cls(pub, priv)
def __init__(self, pub=None, priv=None):
self.priv_key = _load_rsa_private_key(priv)
self.pub_key = pub
def Sign(self, data):
return rsa.sign(data, self.priv_key, 'SHA-1-PREHASHED')
def GetPublicKey(self):
return self.pub_key