Python port of ShadowsocksR
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#!/usr/bin/env python
#
# Copyright 2015 clowwindy
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
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 == 'salsa20':
self.cipher = libsodium.crypto_stream_salsa20_xor_ic
elif cipher_name == '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 = {
'salsa20': (32, 8, SodiumCrypto),
'chacha20': (32, 8, SodiumCrypto),
}
def test_salsa20():
cipher = SodiumCrypto('salsa20', b'k' * 32, b'i' * 16, 1)
decipher = SodiumCrypto('salsa20', b'k' * 32, b'i' * 16, 0)
util.run_cipher(cipher, decipher)
def test_chacha20():
cipher = SodiumCrypto('chacha20', b'k' * 32, b'i' * 16, 1)
decipher = SodiumCrypto('chacha20', b'k' * 32, b'i' * 16, 0)
util.run_cipher(cipher, decipher)
if __name__ == '__main__':
test_chacha20()
test_salsa20()