144 lines
4.3 KiB
Python
144 lines
4.3 KiB
Python
# ciphers.py
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#
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# Copyright (C) 2006-2016 wolfSSL Inc.
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#
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# This file is part of wolfSSL. (formerly known as CyaSSL)
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#
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# wolfSSL is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# wolfSSL 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 General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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from wolfcrypt._ciphers import ffi
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from wolfcrypt._ciphers import lib
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# key direction flags
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ENCRYPTION = 0
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DECRYPTION = 1
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# feedback modes
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MODE_ECB = 1 # Electronic Code Book
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MODE_CBC = 2 # Cipher Block Chaining
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MODE_CFB = 3 # Cipher Feedback
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MODE_OFB = 5 # Output Feedback
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MODE_CTR = 6 # Counter
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FEEDBACK_MODES = [MODE_ECB, MODE_CBC, MODE_CFB, MODE_OFB, MODE_CTR]
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class Cipher(object):
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# Magic object that protects against constructors.
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_JAPANESE_CYBER_SWORD = object()
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def __init__(self, token=""):
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if token is not self._JAPANESE_CYBER_SWORD:
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# PEP 272 -- API for Block Encryption Algorithms v1.0
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raise ValueError("don't construct directly, use new([string])")
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@classmethod
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def new(cls, key, mode, IV=None, **kwargs):
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if mode not in FEEDBACK_MODES:
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raise ValueError("this mode is not supported")
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if mode != MODE_CBC:
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raise ValueError("this mode is not supported by this cipher")
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obj = cls(Cipher._JAPANESE_CYBER_SWORD)
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if obj.key_size:
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if obj.key_size != len(key):
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raise ValueError("key must be %d in length" % obj.key_size)
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elif obj._key_sizes:
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if len(key) not in obj._key_sizes:
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raise ValueError("key must be %s in length" % obj._key_sizes)
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else:
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if not len(key):
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raise ValueError("key must not be 0 in length")
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if IV is not None and len(IV) != obj.block_size:
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raise ValueError("IV must be %d in length" % obj.block_size)
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obj._native_object = ffi.new(obj._native_type)
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obj._key = key
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obj._IV = IV if IV else "\0" * obj.block_size
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return obj
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def encrypt(self, string):
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if not string or len(string) % self.block_size:
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raise ValueError(
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"string must be a multiple of %d in length" % self.block_size)
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cipher = ffi.new(self._native_type)
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ret = "\0" * len(string)
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self._set_key(cipher, ENCRYPTION)
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self._encrypt(cipher, ret, string)
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return ret
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def decrypt(self, string):
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if not string or len(string) % self.block_size:
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raise ValueError(
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"string must be a multiple of %d in length" % self.block_size)
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cipher = ffi.new(self._native_type)
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ret = "\0" * len(string)
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self._set_key(cipher, DECRYPTION)
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self._decrypt(cipher, ret, string)
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return ret
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class Aes(Cipher):
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key_size = None # 16, 24, 32
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_key_sizes = [16, 24, 32]
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block_size = 16
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_native_type = "Aes *"
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def _set_key(self, native_object, direction):
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lib.wc_AesSetKey(
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native_object, self._key, len(self._key), self._IV, direction)
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def _encrypt(self, native_object, destination, source):
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lib.wc_AesCbcEncrypt(native_object, destination, source, len(source))
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def _decrypt(self, native_object, destination, source):
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lib.wc_AesCbcDecrypt(native_object, destination, source, len(source))
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class Des3(Cipher):
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key_size = 24
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block_size = 8
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_native_type = "Des3 *"
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def _set_key(self, native_object, direction):
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lib.wc_Des3_SetKey(native_object, self._key, self._IV, direction)
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def _encrypt(self, native_object, destination, source):
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lib.wc_Des3_CbcEncrypt(native_object, destination, source, len(source))
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def _decrypt(self, native_object, destination, source):
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lib.wc_Des3_CbcDecrypt(native_object, destination, source, len(source))
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