Helmut Jarausch wrote:
Hi,
I've just tried to write a simple example using PyCrypto's
AES (CBC mode)
#!/usr/bin/python
from Crypto.Cipher import AES
PWD='abcdefghijklmnop'
Initial16bytes='0123456789ABCDEF'
crypt = AES.new(PWD, AES.MODE_CBC,Initial16bytes)
# crypt = AES.new(PWD, AES.MODE_ECB)
txt = 'ea523a664dabaa4476d31226a1e3bab0'
c = crypt.encrypt(txt)
txt_plain=crypt.decrypt(c)
print txt_plain
Unfortunately, txt_plain differs from txt - why?
(Using MODE_ECB does work however)
I just discovered that the following variant seems to work
crypt = AES.new(PWD, AES.MODE_CBC,Initial16bytes)
c = crypt.encrypt(txt)
crypt = AES.new(PWD, AES.MODE_CBC,Initial16bytes) # <<< re-initialize
txt_plain=crypt.decrypt(c)
So, the crypt object seems to keep some state.
I haven't seen this mentioned in the documentation.
Helmut.
--
Helmut Jarausch
Lehrstuhl fuer Numerische Mathematik
RWTH - Aachen University
D 52056 Aachen, Germany
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