Rijndael sanity check?

Richard Hodges rh at matriplex.com
Wed Jul 18 18:38:56 UTC 2007


On Wednesday 18 July 2007 12:26 pm, Stefan Farfeleder wrote:
> On Wed, Jul 18, 2007 at 12:06:35PM -0600, Richard Hodges wrote:
> > > ./aes_test
> >
> > Using key: 2b 7e 15 16 28 ae d2 a6 ab f7 15 88 09 cf 4f 3c
> >
> > 920F0CE0A9A96BB9D8416962BDBBAA7C
> > decr: 92 0f 0c e0 a9 a9 6b b9 d8 41 69 62 bd bb aa 7c
> > encr: c9 3d 42 18 70 34 ce a8 67 1b 88 43 10 00 d1 8c
>
>                                                ^^
>
> > c74601001001000000000054006b51FF
> > decr: c7 46 01 00 10 01 00 00 00 00 00 54 00 6b 51 ff
> > encr: c9 3d 42 18 70 34 ce a8 67 1b 88 43 10 a2 d1 8c
>
>                                                ^^
> It seems to be different.

Good eye, and thanks!

It did not occur to me that the difference would be so subtle as three bits, 
as I normally expect encryption to propagate even small bit differences 
across the entire block.  Oops!  Bad assumption!

Now it looks like I have a bug to find in my own code, but that is so much 
better than suspecting a problem somewhere else! :)

Thanks again,
-Richard



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