103 lines
3.3 KiB
Python
103 lines
3.3 KiB
Python
# (C) Copyright 2016 Mirantis, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import hashlib
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives.ciphers import algorithms
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from cryptography.hazmat.primitives.ciphers import Cipher
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from cryptography.hazmat.primitives.ciphers import modes
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from os import urandom
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SALT_HEADER = 'Salted__'
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AES256_KEY_LENGTH = 32
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BS = 16 # static 16 bytes, 128 bits for AES
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class AESCipher(object):
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"""
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Base class for encrypt/decrypt activities.
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"""
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def __init__(self, pass_file):
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self._password = self._get_pass_from_file(pass_file)
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self._salt = None
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self.cipher = None
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@staticmethod
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def _get_pass_from_file(pass_file):
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with open(pass_file) as p_file:
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password = p_file.readline()
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return password
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@staticmethod
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def _derive_key_and_iv(password, salt, key_length, iv_length):
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d = d_i = b''
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while len(d) < key_length + iv_length:
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md5_str = d_i + password + salt
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d_i = hashlib.md5(md5_str).digest()
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d += d_i
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return d[:key_length], d[key_length:key_length + iv_length]
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class AESEncrypt(AESCipher):
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"""
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Encrypts chucks of data using AES-256 algorithm.
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OpenSSL compatible.
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"""
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def __init__(self, pass_file):
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super(AESEncrypt, self).__init__(pass_file)
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self._salt = urandom(BS - len(SALT_HEADER))
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key, iv = self._derive_key_and_iv(self._password,
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self._salt,
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AES256_KEY_LENGTH,
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BS)
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self.cipher = Cipher(algorithms.AES(key),
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modes.CFB(iv),
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backend=default_backend())
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def generate_header(self):
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return SALT_HEADER + self._salt
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def encrypt(self, data):
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encryptor = self.cipher.encryptor()
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return encryptor.update(data) + encryptor.finalize()
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class AESDecrypt(AESCipher):
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"""
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Decrypts chucks of data using AES-256 algorithm.
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OpenSSL compatible.
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"""
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def __init__(self, pass_file, salt):
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super(AESDecrypt, self).__init__(pass_file)
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self._salt = self._prepare_salt(salt)
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key, iv = self._derive_key_and_iv(self._password,
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self._salt,
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AES256_KEY_LENGTH,
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BS)
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self.cipher = Cipher(algorithms.AES(key),
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modes.CFB(iv),
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backend=default_backend())
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@staticmethod
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def _prepare_salt(salt):
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return salt[len(SALT_HEADER):]
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def decrypt(self, data):
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decryptor = self.cipher.decryptor()
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return decryptor.update(data) + decryptor.finalize()
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