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# -*- coding: utf-8 -*-
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# Copyright (C) 2014-2016 RhodeCode GmbH
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License, version 3
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# (only), as published by the Free Software Foundation.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# This program is dual-licensed. If you wish to learn more about the
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# RhodeCode Enterprise Edition, including its added features, Support services,
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# and proprietary license terms, please see https://rhodecode.com/licenses/
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"""
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Generic encryption library for RhodeCode
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"""
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import base64
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from Crypto.Cipher import AES
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from Crypto import Random
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from Crypto.Hash import HMAC, SHA256
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from rhodecode.lib.utils2 import safe_str
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class SignatureVerificationError(Exception):
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pass
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class InvalidDecryptedValue(str):
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def __new__(cls, content):
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"""
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This will generate something like this::
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<InvalidDecryptedValue(QkWusFgLJXR6m42v...)>
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And represent a safe indicator that encryption key is broken
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"""
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content = '<{}({}...)>'.format(cls.__name__, content[:16])
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return str.__new__(cls, content)
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class AESCipher(object):
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def __init__(self, key, hmac=False, strict_verification=True):
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if not key:
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raise ValueError('passed key variable is empty')
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self.strict_verification = strict_verification
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self.block_size = 32
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self.hmac_size = 32
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self.hmac = hmac
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self.key = SHA256.new(safe_str(key)).digest()
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self.hmac_key = SHA256.new(self.key).digest()
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def verify_hmac_signature(self, raw_data):
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org_hmac_signature = raw_data[-self.hmac_size:]
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data_without_sig = raw_data[:-self.hmac_size]
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recomputed_hmac = HMAC.new(
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self.hmac_key, data_without_sig, digestmod=SHA256).digest()
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return org_hmac_signature == recomputed_hmac
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def encrypt(self, raw):
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raw = self._pad(raw)
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iv = Random.new().read(AES.block_size)
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cipher = AES.new(self.key, AES.MODE_CBC, iv)
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enc_value = cipher.encrypt(raw)
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hmac_signature = ''
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if self.hmac:
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# compute hmac+sha256 on iv + enc text, we use
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# encrypt then mac method to create the signature
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hmac_signature = HMAC.new(
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self.hmac_key, iv + enc_value, digestmod=SHA256).digest()
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return base64.b64encode(iv + enc_value + hmac_signature)
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def decrypt(self, enc):
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enc_org = enc
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enc = base64.b64decode(enc)
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if self.hmac and len(enc) > self.hmac_size:
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if self.verify_hmac_signature(enc):
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# cut off the HMAC verification digest
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enc = enc[:-self.hmac_size]
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else:
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if self.strict_verification:
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raise SignatureVerificationError(
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"Encryption signature verification failed. "
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"Please check your secret key, and/or encrypted value. "
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"Secret key is stored as "
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"`rhodecode.encrypted_values.secret` or "
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"`beaker.session.secret` inside .ini file")
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return InvalidDecryptedValue(enc_org)
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iv = enc[:AES.block_size]
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cipher = AES.new(self.key, AES.MODE_CBC, iv)
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return self._unpad(cipher.decrypt(enc[AES.block_size:]))
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def _pad(self, s):
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return (s + (self.block_size - len(s) % self.block_size)
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* chr(self.block_size - len(s) % self.block_size))
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@staticmethod
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def _unpad(s):
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return s[:-ord(s[len(s)-1:])]
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