text: #!/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
  
  import logging
  from ctypes import CDLL, c_char_p, c_int, c_long, byref,\
      create_string_buffer, c_void_p
  
  __all__ = ['ciphers']
  
  libcrypto = None
  loaded = False
  
  buf_size = 2048
  
  
  def load_openssl():
      global loaded, libcrypto, buf
  
      from ctypes.util import find_library
      for p in ('crypto', 'eay32', 'libeay32'):
          libcrypto_path = find_library(p)
          if libcrypto_path:
              break
      else:
          raise Exception('libcrypto(OpenSSL) not found')
      logging.info('loading libcrypto from %s', libcrypto_path)
      libcrypto = CDLL(libcrypto_path)
      libcrypto.EVP_get_cipherbyname.restype = c_void_p
      libcrypto.EVP_CIPHER_CTX_new.restype = c_void_p
  
      libcrypto.EVP_CipherInit_ex.argtypes = (c_void_p, c_void_p, c_char_p,
                                              c_char_p, c_char_p, c_int)
  
      libcrypto.EVP_CipherUpdate.argtypes = (c_void_p, c_void_p, c_void_p,
                                             c_char_p, c_int)
  
      libcrypto.EVP_CIPHER_CTX_cleanup.argtypes = (c_void_p,)
      libcrypto.EVP_CIPHER_CTX_free.argtypes = (c_void_p,)
      if hasattr(libcrypto, 'OpenSSL_add_all_ciphers'):
          libcrypto.OpenSSL_add_all_ciphers()
  
      buf = create_string_buffer(buf_size)
      loaded = True
  
  
  def load_cipher(cipher_name):
      func_name = b'EVP_' + cipher_name.replace(b'-', b'_')
      if bytes != str:
          func_name = str(func_name, 'utf-8')
      cipher = getattr(libcrypto, func_name, None)
      if cipher:
          cipher.restype = c_void_p
          return cipher()
      return None
  
  
  class CtypesCrypto(object):
      def __init__(self, cipher_name, key, iv, op):
          if not loaded:
              load_openssl()
          self._ctx = None
          cipher = libcrypto.EVP_get_cipherbyname(cipher_name)
          if not cipher:
              cipher = load_cipher(cipher_name)
          if not cipher:
              raise Exception('cipher %s not found in libcrypto' % cipher_name)
          key_ptr = c_char_p(key)
          iv_ptr = c_char_p(iv)
          self._ctx = libcrypto.EVP_CIPHER_CTX_new()
          if not self._ctx:
              raise Exception('can not create cipher context')
          r = libcrypto.EVP_CipherInit_ex(self._ctx, cipher, None,
                                          key_ptr, iv_ptr, c_int(op))
          if not r:
              self.clean()
              raise Exception('can not initialize cipher context')
  
      def update(self, data):
          global buf_size, buf
          cipher_out_len = c_long(0)
          l = len(data)
          if buf_size < l:
              buf_size = l * 2
              buf = create_string_buffer(buf_size)
          libcrypto.EVP_CipherUpdate(self._ctx, byref(buf),
                                     byref(cipher_out_len), c_char_p(data), l)
          # buf is copied to a str object when we access buf.raw
          return buf.raw[:cipher_out_len.value]
  
      def __del__(self):
          self.clean()
  
      def clean(self):
          if self._ctx:
              libcrypto.EVP_CIPHER_CTX_cleanup(self._ctx)
              libcrypto.EVP_CIPHER_CTX_free(self._ctx)
  
  
  ciphers = {
      b'aes-128-cfb': (16, 16, CtypesCrypto),
      b'aes-192-cfb': (24, 16, CtypesCrypto),
      b'aes-256-cfb': (32, 16, CtypesCrypto),
      b'aes-128-ofb': (16, 16, CtypesCrypto),
      b'aes-192-ofb': (24, 16, CtypesCrypto),
      b'aes-256-ofb': (32, 16, CtypesCrypto),
      b'aes-128-ctr': (16, 16, CtypesCrypto),
      b'aes-192-ctr': (24, 16, CtypesCrypto),
      b'aes-256-ctr': (32, 16, CtypesCrypto),
      b'aes-128-cfb8': (16, 16, CtypesCrypto),
      b'aes-192-cfb8': (24, 16, CtypesCrypto),
      b'aes-256-cfb8': (32, 16, CtypesCrypto),
      b'aes-128-cfb1': (16, 16, CtypesCrypto),
      b'aes-192-cfb1': (24, 16, CtypesCrypto),
      b'aes-256-cfb1': (32, 16, CtypesCrypto),
      b'bf-cfb': (16, 8, CtypesCrypto),
      b'camellia-128-cfb': (16, 16, CtypesCrypto),
      b'camellia-192-cfb': (24, 16, CtypesCrypto),
      b'camellia-256-cfb': (32, 16, CtypesCrypto),
      b'cast5-cfb': (16, 8, CtypesCrypto),
      b'des-cfb': (8, 8, CtypesCrypto),
      b'idea-cfb': (16, 8, CtypesCrypto),
      b'rc2-cfb': (16, 8, CtypesCrypto),
      b'rc4': (16, 0, CtypesCrypto),
      b'seed-cfb': (16, 16, CtypesCrypto),
  }
  
  
  def run_method(method):
      from shadowsocksr.crypto import util
  
      cipher = CtypesCrypto(method, b'k' * 32, b'i' * 16, 1)
      decipher = CtypesCrypto(method, b'k' * 32, b'i' * 16, 0)
  
      util.run_cipher(cipher, decipher)
  
  
  def test_aes_128_cfb():
      run_method(b'aes-128-cfb')
  
  
  def test_aes_256_cfb():
      run_method(b'aes-256-cfb')
  
  
  def test_aes_128_cfb8():
      run_method(b'aes-128-cfb8')
  
  
  def test_aes_256_ofb():
      run_method(b'aes-256-ofb')
  
  
  def test_aes_256_ctr():
      run_method(b'aes-256-ctr')
  
  
  def test_bf_cfb():
      run_method(b'bf-cfb')
  
  
  def test_rc4():
      run_method(b'rc4')
  
  
  if __name__ == '__main__':
      test_aes_128_cfb()
  