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encrypt.py
138 lines | 4.7 KiB | text/x-python | PythonLexer
# -*- coding: utf-8 -*-
# Copyright (C) 2014-2020 RhodeCode GmbH
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License, version 3
# (only), as published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# This program is dual-licensed. If you wish to learn more about the
# RhodeCode Enterprise Edition, including its added features, Support services,
# and proprietary license terms, please see https://rhodecode.com/licenses/
"""
Generic encryption library for RhodeCode
"""
import base64
from Crypto.Cipher import AES
from Crypto import Random
from Crypto.Hash import HMAC, SHA256
from rhodecode.lib.utils2 import safe_str
class SignatureVerificationError(Exception):
pass
class InvalidDecryptedValue(str):
def __new__(cls, content):
"""
This will generate something like this::
<InvalidDecryptedValue(QkWusFgLJXR6m42v...)>
And represent a safe indicator that encryption key is broken
"""
content = '<{}({}...)>'.format(cls.__name__, content[:16])
return str.__new__(cls, content)
class AESCipher(object):
def __init__(self, key, hmac=False, strict_verification=True):
if not key:
raise ValueError('passed key variable is empty')
self.strict_verification = strict_verification
self.block_size = 32
self.hmac_size = 32
self.hmac = hmac
self.key = SHA256.new(safe_str(key)).digest()
self.hmac_key = SHA256.new(self.key).digest()
def verify_hmac_signature(self, raw_data):
org_hmac_signature = raw_data[-self.hmac_size:]
data_without_sig = raw_data[:-self.hmac_size]
recomputed_hmac = HMAC.new(
self.hmac_key, data_without_sig, digestmod=SHA256).digest()
return org_hmac_signature == recomputed_hmac
def encrypt(self, raw):
raw = self._pad(raw)
iv = Random.new().read(AES.block_size)
cipher = AES.new(self.key, AES.MODE_CBC, iv)
enc_value = cipher.encrypt(raw)
hmac_signature = ''
if self.hmac:
# compute hmac+sha256 on iv + enc text, we use
# encrypt then mac method to create the signature
hmac_signature = HMAC.new(
self.hmac_key, iv + enc_value, digestmod=SHA256).digest()
return base64.b64encode(iv + enc_value + hmac_signature)
def decrypt(self, enc):
enc_org = enc
enc = base64.b64decode(enc)
if self.hmac and len(enc) > self.hmac_size:
if self.verify_hmac_signature(enc):
# cut off the HMAC verification digest
enc = enc[:-self.hmac_size]
else:
if self.strict_verification:
raise SignatureVerificationError(
"Encryption signature verification failed. "
"Please check your secret key, and/or encrypted value. "
"Secret key is stored as "
"`rhodecode.encrypted_values.secret` or "
"`beaker.session.secret` inside .ini file")
return InvalidDecryptedValue(enc_org)
iv = enc[:AES.block_size]
cipher = AES.new(self.key, AES.MODE_CBC, iv)
return self._unpad(cipher.decrypt(enc[AES.block_size:]))
def _pad(self, s):
return (s + (self.block_size - len(s) % self.block_size)
* chr(self.block_size - len(s) % self.block_size))
@staticmethod
def _unpad(s):
return s[:-ord(s[len(s)-1:])]
def validate_and_get_enc_data(enc_data, enc_key, enc_strict_mode):
parts = enc_data.split('$', 3)
if not len(parts) == 3:
# probably not encrypted values
return enc_data
else:
if parts[0] != 'enc':
# parts ok but without our header ?
return enc_data
# at that stage we know it's our encryption
if parts[1] == 'aes':
decrypted_data = AESCipher(enc_key).decrypt(parts[2])
elif parts[1] == 'aes_hmac':
decrypted_data = AESCipher(
enc_key, hmac=True,
strict_verification=enc_strict_mode).decrypt(parts[2])
else:
raise ValueError(
'Encryption type part is wrong, must be `aes` '
'or `aes_hmac`, got `%s` instead' % (parts[1]))
return decrypted_data