[pycrypto] AES, MODE_CTR

[Legrandin]

>Thanks Richard. Now working
>   def test_AES5(self):
>        pt=b' '*10
>        ctr=Counter.new(128)
>        iv = Random.new().read(AES.block_size)
>        cipher = AES.new(b' '*16, AES.MODE_CTR, IV=iv, counter=ctr)
>        ct = cipher.encrypt(pt)
>        ctrr=Counter.new(128)
>        decipher = AES.new(b' '*16, AES.MODE_CTR, IV=iv, counter=ctrr)
>        ptr = decipher.decrypt(ct)
>        self.assertEqual(pt,ptr)
> iv added as suggested.

Actually, the IV parameter is ignored in Counter mode.
If you want to add a nonce to the counter block you must pass it to
the Counter class:

  nonce = Random.new().read(8)
  ctr = Counter.new(64, nonce)
  cipher = AES.new(b' '*16, AES.MODE_CTR, counter=ctr)

The counter block is then made up by 64 bits of nonce and 64 bits of counter.

PS: I think I get 1 out of 3 messages out of this mailing list.