Re: AES 256 key and anti-key

On Apr 4, 5:19 am, Ertugrul Söylemez <e...@xxxxxxxx> wrote:
biject <biject.b...@xxxxxxxxx> wrote:
Yes but that still leaves at least 2 way to pick which
permutaion to which key, I don't see where you get the idea that
you have to pick in a random way to allow for a nonzero chance of
repeat when its not nexessiary

That non-zero chance is a natural consequence of picking randomly.
The point is that picking randomly is the method with least possible
side effects. With every bit of structure you introduce, you give a
potential attacker information.

That is where we differ i think you can always decrease your set by
the amount of mappings that go to other keys. I agree that structure
in the permutations can be a weakness. But not allowing duplicate
mappings is not reduceing structure in my view. But maybe I am wrong.
But it appears so balck and white I am willing to live with the
difference until someone shows a proof or example where it would
weaken it.

Now tell me, how would you ensure/prove an injective mapping from a
large key-space to an even much more larger permutation-space (where
even the cardinality is such a large number that you couldn't store it)?
How would you keep that mapping pseudo-random at the same time?


I don't know how to tell if something like AES is designed in a way
that has it or not. I know that since scott19u can be run in a way
that it can produce every possible single cycle transform that It is
not hard to ensure no repeats. But its only for a 19bit sub-buffer.
For any actually file regardless of length not sure how many keys
would produce the same mappings for various files. I am not sure if
only allowing a single cycle is also bad for the way its used..

What I was wondering does anyone know if there are duplicate keys
that work exactly the same in AES I realize if there is that its
mostly likely a small subset. But either it has duplicates or it
doesn't since its fully defined. I also realize if it does its most
likely a very very small subset.



That isn't necessarily a contradiction, but really, how would you do it?
Do you see why I don't agree?

I think I am starting to see why you blieve an ideal cipher might
have there characteristics I don;t know how you know that AES has
this. unless there is a proof just for AES or if someone has actually
found two keys that map the same.


Regards,
Ertugrul.

--http://ertes.de/

David A. Scott
--
My Crypto code
http://bijective.dogma.net/crypto/scott19u.zip
http://www.jim.com/jamesd/Kong/scott19u.zip old version
My Compression code http://bijective.dogma.net/
**TO EMAIL ME drop the roman "five" **
Disclaimer:I am in no way responsible for any of the statements
made in the above text. For all I know I might be drugged.
As a famous person once said "any cryptograhic
system is only as strong as its weakest link"
.

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