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140 lines
4.1 KiB
140 lines
4.1 KiB
#!/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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