DES3-CBC gotcha encrypt/decrypt on same object

[ine ya]

I just spent quite a while trying to use the same object to encrypt something and decrypt the result. As I later figured out, this doesn't work and although this is not a bug, I would kindly ask to mention this in documentation, possibly to include example similar to one below.

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#!/usr/bin/python

from Crypto.Cipher import DES3
obj=DES3.new('a'*16, DES3.MODE_CBC)
plain="Guido van Rossum is a space alien."

ciph=obj.encrypt(plain+'XXXXXX')
print repr(ciph)

obj2=DES3.new('a'*16, DES3.MODE_CBC)

print obj.decrypt(ciph) # doesn't work -> avoid!
print obj2.decrypt(ciph) # works
========================================

[Darsey Litzenberger (dlitz)]

Good idea.

Done: https://github.com/dlitz/pycrypto/commit/b9658a26003ebfcfce1804a2363a29354799b47e

[Darsey Litzenberger (dlitz)]

Released in PyCrypto 2.4.