Python port of ShadowsocksR
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#!/usr/bin/env python
# Copyright (c) 2014 clowwindy
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
from __future__ import absolute_import, division, print_function, \
with_statement
from ctypes import c_char_p, c_int, c_ulonglong, byref, \
create_string_buffer, c_void_p
from shadowsocks.crypto import util
__all__ = ['ciphers']
libsodium = None
loaded = False
buf_size = 2048
# for salsa20 and chacha20
BLOCK_SIZE = 64
def load_libsodium():
global loaded, libsodium, buf
libsodium = util.find_library('sodium', 'crypto_stream_salsa20_xor_ic',
'libsodium')
if libsodium is None:
raise Exception('libsodium not found')
libsodium.crypto_stream_salsa20_xor_ic.restype = c_int
libsodium.crypto_stream_salsa20_xor_ic.argtypes = (c_void_p, c_char_p,
c_ulonglong,
c_char_p, c_ulonglong,
c_char_p)
libsodium.crypto_stream_chacha20_xor_ic.restype = c_int
libsodium.crypto_stream_chacha20_xor_ic.argtypes = (c_void_p, c_char_p,
c_ulonglong,
c_char_p, c_ulonglong,
c_char_p)
buf = create_string_buffer(buf_size)
loaded = True
class SodiumCrypto(object):
def __init__(self, cipher_name, key, iv, op):
if not loaded:
load_libsodium()
self.key = key
self.iv = iv
self.key_ptr = c_char_p(key)
self.iv_ptr = c_char_p(iv)
if cipher_name == b'salsa20':
self.cipher = libsodium.crypto_stream_salsa20_xor_ic
elif cipher_name == b'chacha20':
self.cipher = libsodium.crypto_stream_chacha20_xor_ic
else:
raise Exception('Unknown cipher')
# byte counter, not block counter
self.counter = 0
def update(self, data):
global buf_size, buf
l = len(data)
# we can only prepend some padding to make the encryption align to
# blocks
padding = self.counter % BLOCK_SIZE
if buf_size < padding + l:
buf_size = (padding + l) * 2
buf = create_string_buffer(buf_size)
if padding:
data = (b'\0' * padding) + data
self.cipher(byref(buf), c_char_p(data), padding + l,
self.iv_ptr, int(self.counter / BLOCK_SIZE), self.key_ptr)
self.counter += l
# buf is copied to a str object when we access buf.raw
# strip off the padding
return buf.raw[padding:padding + l]
ciphers = {
b'salsa20': (32, 8, SodiumCrypto),
b'chacha20': (32, 8, SodiumCrypto),
}
def test_salsa20():
cipher = SodiumCrypto(b'salsa20', b'k' * 32, b'i' * 16, 1)
decipher = SodiumCrypto(b'salsa20', b'k' * 32, b'i' * 16, 0)
util.run_cipher(cipher, decipher)
def test_chacha20():
cipher = SodiumCrypto(b'chacha20', b'k' * 32, b'i' * 16, 1)
decipher = SodiumCrypto(b'chacha20', b'k' * 32, b'i' * 16, 0)
util.run_cipher(cipher, decipher)
if __name__ == '__main__':
test_chacha20()
test_salsa20()