The symmetric ciphers
Robert J. Hansen
rjh at sixdemonbag.org
Thu Oct 31 04:52:32 CET 2013
On 10/30/2013 7:20 PM, Johan Wevers wrote:
> That's because ROT(N) is a group.
Yes, but good luck answering the inevitable next two questions: "what's
a group?" and "how do we know if something's a group?" You very quickly
run into some complicated higher-level maths, and that's something best
> I don't know wether the other symmetric ciphers are a group though,
> but I'm sure someone has investigated that.
There is no single answer to this. The "other symmetric ciphers" need
to be evaluated combinatorically: for instance, are AES128, 3DES and
Camellia a group? That answer may be different from AES192, 3DES and
Given there are 11 different symmetric algorithms as of 2.0.22, figuring
out all known-safe 3-cipher selections would require us to investigate
165 different combinations. Frankly, I don't feel like doing that much
> Assuming that the same key is used for all that is.
No. I'm quite happy with my blanket statement: cryptographic algorithms
are subtle and should be left alone. If you're Don Coppersmith then I
think you should feel free to get down with your bad self, but otherwise
this entire line of inquiry is one that I think goes nowhere good.
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