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120 lines
3.7 KiB
120 lines
3.7 KiB
#!/usr/bin/env python
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#
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# Copyright 2015 clowwindy
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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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from __future__ import absolute_import, division, print_function, \
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with_statement
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from ctypes import c_char_p, c_int, c_ulonglong, byref, \
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create_string_buffer, c_void_p
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from shadowsocks.crypto import util
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__all__ = ['ciphers']
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libsodium = None
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loaded = False
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buf_size = 2048
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# for salsa20 and chacha20
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BLOCK_SIZE = 64
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def load_libsodium():
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global loaded, libsodium, buf
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libsodium = util.find_library('sodium', 'crypto_stream_salsa20_xor_ic',
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'libsodium')
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if libsodium is None:
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raise Exception('libsodium not found')
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libsodium.crypto_stream_salsa20_xor_ic.restype = c_int
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libsodium.crypto_stream_salsa20_xor_ic.argtypes = (c_void_p, c_char_p,
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c_ulonglong,
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c_char_p, c_ulonglong,
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c_char_p)
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libsodium.crypto_stream_chacha20_xor_ic.restype = c_int
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libsodium.crypto_stream_chacha20_xor_ic.argtypes = (c_void_p, c_char_p,
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c_ulonglong,
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c_char_p, c_ulonglong,
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c_char_p)
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buf = create_string_buffer(buf_size)
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loaded = True
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class SodiumCrypto(object):
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def __init__(self, cipher_name, key, iv, op):
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if not loaded:
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load_libsodium()
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self.key = key
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self.iv = iv
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self.key_ptr = c_char_p(key)
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self.iv_ptr = c_char_p(iv)
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if cipher_name == 'salsa20':
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self.cipher = libsodium.crypto_stream_salsa20_xor_ic
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elif cipher_name == 'chacha20':
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self.cipher = libsodium.crypto_stream_chacha20_xor_ic
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else:
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raise Exception('Unknown cipher')
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# byte counter, not block counter
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self.counter = 0
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def update(self, data):
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global buf_size, buf
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l = len(data)
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# we can only prepend some padding to make the encryption align to
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# blocks
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padding = self.counter % BLOCK_SIZE
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if buf_size < padding + l:
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buf_size = (padding + l) * 2
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buf = create_string_buffer(buf_size)
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if padding:
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data = (b'\0' * padding) + data
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self.cipher(byref(buf), c_char_p(data), padding + l,
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self.iv_ptr, int(self.counter / BLOCK_SIZE), self.key_ptr)
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self.counter += l
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# buf is copied to a str object when we access buf.raw
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# strip off the padding
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return buf.raw[padding:padding + l]
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ciphers = {
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'salsa20': (32, 8, SodiumCrypto),
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'chacha20': (32, 8, SodiumCrypto),
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}
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def test_salsa20():
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cipher = SodiumCrypto('salsa20', b'k' * 32, b'i' * 16, 1)
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decipher = SodiumCrypto('salsa20', b'k' * 32, b'i' * 16, 0)
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util.run_cipher(cipher, decipher)
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def test_chacha20():
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cipher = SodiumCrypto('chacha20', b'k' * 32, b'i' * 16, 1)
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decipher = SodiumCrypto('chacha20', b'k' * 32, b'i' * 16, 0)
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util.run_cipher(cipher, decipher)
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if __name__ == '__main__':
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test_chacha20()
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test_salsa20()
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