clowwindy
10 years ago
5 changed files with 41 additions and 183 deletions
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#!/usr/bin/env python |
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# Copyright (c) 2014 clowwindy |
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# |
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# Permission is hereby granted, free of charge, to any person obtaining a copy |
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# of this software and associated documentation files (the "Software"), to deal |
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# in the Software without restriction, including without limitation the rights |
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
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# copies of the Software, and to permit persons to whom the Software is |
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# furnished to do so, subject to the following conditions: |
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# |
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# The above copyright notice and this permission notice shall be included in |
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# all copies or substantial portions of the Software. |
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# |
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
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# SOFTWARE. |
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from __future__ import absolute_import, division, print_function, \ |
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with_statement |
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import struct |
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import logging |
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import sys |
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slow_xor = False |
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imported = False |
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salsa20 = None |
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numpy = None |
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BLOCK_SIZE = 16384 |
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def run_imports(): |
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global imported, slow_xor, salsa20, numpy |
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if not imported: |
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imported = True |
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try: |
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numpy = __import__('numpy') |
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except ImportError: |
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logging.error('can not import numpy, using SLOW XOR') |
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logging.error('please install numpy if you use salsa20') |
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slow_xor = True |
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try: |
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salsa20 = __import__('salsa20') |
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except ImportError: |
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logging.error('you have to install salsa20 before you use salsa20') |
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sys.exit(1) |
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def numpy_xor(a, b): |
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if slow_xor: |
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return py_xor_str(a, b) |
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dtype = numpy.byte |
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if len(a) % 4 == 0: |
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dtype = numpy.uint32 |
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elif len(a) % 2 == 0: |
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dtype = numpy.uint16 |
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ab = numpy.frombuffer(a, dtype=dtype) |
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bb = numpy.frombuffer(b, dtype=dtype) |
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c = numpy.bitwise_xor(ab, bb) |
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r = c.tostring() |
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return r |
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def py_xor_str(a, b): |
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c = [] |
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if bytes == str: |
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for i in range(0, len(a)): |
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c.append(chr(ord(a[i]) ^ ord(b[i]))) |
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return ''.join(c) |
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else: |
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for i in range(0, len(a)): |
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c.append(a[i] ^ b[i]) |
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return bytes(c) |
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class Salsa20Cipher(object): |
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"""a salsa20 CTR implemetation, provides m2crypto like cipher API""" |
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def __init__(self, alg, key, iv, op, key_as_bytes=0, d=None, salt=None, |
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i=1, padding=1): |
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run_imports() |
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if alg != b'salsa20-ctr': |
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raise Exception('unknown algorithm') |
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self._key = key |
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self._nonce = struct.unpack('<Q', iv)[0] |
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self._pos = 0 |
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self._next_stream() |
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def _next_stream(self): |
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self._nonce &= 0xFFFFFFFFFFFFFFFF |
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self._stream = salsa20.Salsa20_keystream(BLOCK_SIZE, |
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struct.pack('<Q', |
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self._nonce), |
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self._key) |
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self._nonce += 1 |
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def update(self, data): |
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results = [] |
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while True: |
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remain = BLOCK_SIZE - self._pos |
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cur_data = data[:remain] |
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cur_data_len = len(cur_data) |
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cur_stream = self._stream[self._pos:self._pos + cur_data_len] |
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self._pos = self._pos + cur_data_len |
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data = data[remain:] |
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results.append(numpy_xor(cur_data, cur_stream)) |
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if self._pos >= BLOCK_SIZE: |
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self._next_stream() |
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self._pos = 0 |
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if not data: |
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break |
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return b''.join(results) |
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ciphers = { |
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b'salsa20-ctr': (32, 8, Salsa20Cipher), |
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} |
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def test(): |
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from shadowsocks.crypto import util |
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cipher = Salsa20Cipher(b'salsa20-ctr', b'k' * 32, b'i' * 8, 1) |
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decipher = Salsa20Cipher(b'salsa20-ctr', b'k' * 32, b'i' * 8, 1) |
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util.run_cipher(cipher, decipher) |
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if __name__ == '__main__': |
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test() |
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