python - Python 中的双鱼加密

Question

我有一个测试工具，它使用 Twofish 作为加密算法，在将数据发送到服务器之前对数据进行加密。代码是用 C++ 编写的，并使用 Bruce Schneier 的优化 C 实现 (https://www.schneier.com/code/twofish-optimized-c.zip)。我需要将此工具移植到 Python，并且我正在使用 twofish 模块 ( https://pypi.python.org/pypi/twofish/0.3.0 )。我可以加密和解密 16 个字符长度的字符串，但对于其他字符串长度，它会给出错误“ValueError:无效 block 长度”。

如何使用 Python 的 Twofish 模块加密和解密大数据？

>>> from twofish import Twofish
>>> key = binascii.unhexlify('8CACBE276491F6FF4B1EC0E9CFD52E76')
>>> t = Twofish(key)
>>> cipher_text = T.encrypt('deadbeaf12345678')
>>> plain_text = t.decrypt(cipher_text)
>>> plain_text
'deadbeaf12345678'
>>> cipher_text = t.encrypt('deadbeaf12345678hello world 1234')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/site-packages/twofish.py", line 69, in encrypt
    raise ValueError('invalid block length')
ValueError: invalid block length

更新:我正在尝试针对此问题的另一种解决方案。我从 Bruce Schneier 的优化 C 实现 (https://www.schneier.com/code/twofish-optimized-c.zip) 创建了一个 Windows DLL，twofish.dll。此外，我还使用 __declspec(dllexport) 导出了用于编码和解码成员函数的包装函数。

我正在使用 ctype.CDLL 函数在 Python 中加载此 DLL。encode函数的原型(prototype)是:

__declspec(dllexport) int encode(unsigned char *key, unsigned char *in, unsigned int inlen, unsigned char *out, unsigned int outbuflen, unsigned int& outlen)

我应该如何在 Python 脚本中定义参数类型？

import ctypes
import binascii
import requests

twofish_dll = ctypes.CDLL("twofish.dll")

encode = twofish_dll.encode

f = open('test.xml', 'r')
plain_text = f.read()
f.close()

cipher_text = ctypes.create_string_buffer(8192)
cipher_text_lenght = (ctypes.c_uint)()

KCS = '8CACBE276491F6FF4B1EC0E9CFD52E76'
key = binascii.unhexlify(KCS)

encode.argtypes = [ctypes.c_char_p, ctypes.c_char_p, ctypes.c_uint, ctypes.c_char_p, ctypes.c_uint, ctypes.POINTER(ctypes.c_uint)]
encode(ctypes.c_char_p(key), ctypes.c_char_p(plain_text), len(plain_text), cipher_text, 8192, ctypes.byref(cipher_text_lenght))

执行上面的代码会抛出以下错误:

Traceback (most recent call last):
  File "C:\Data\sepm_test.py", line 21, in <module>
    encode(ctypes.c_char_p(key), ctypes.c_char_p(plain_text), len(plain_text), cipher_text, 8192, ctypes.byref(cipher_text_lenght))
TypeError: bytes or integer address expected instead of str instance

Answer 1

Twofish 是一种分组密码，一次只能加密 16 个八位字节。郭思the documentation :

Create a twofish.Twofish instance with a key of length ]0, 32] and then use the encrypt and decrypt methods on 16 bytes blocks.

All values must be binary strings (str on Python 2, bytes on Python 3)

[WARNING] this should be used in a sensible cipher mode, like CTR or CBC. If you don't know what this means, you should probably use a higher level library.

注意警告，CBC or CTR is not rocket science ，但如果您天真地使用 Twofish，它的安全性就会受到严重威胁。