[PYTHON-CRYPTO] things missing from PEP 272

Bram Cohen bram at GAWTH.COM
Tue Mar 19 02:23:19 CET 2002


Zooko wrote:

>  Bram Cohen <bram at GAWTH.COM> wrote:
> >
> > The API for OFB is obvious, but the one for CTR is considerably less so.
> > My suggestion is to have the IV be the first block to be encrypted,
>
> Err...  Wouldn't that mean that if you sent a message consisting of BLOCK0 and
> BLOCK1, and then you sent a message consisting of BLOCK0 and BLOCK2, that both
> messages would be completely readable to a passive eavesdroppper?  :-)

Well, yes - you aren't supposed to reuse keys for CTR mode.

-Bram Cohen

"Markets can remain irrational longer than you can remain solvent"
                                        -- John Maynard Keynes





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