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Dec
22
comment AES key length greater than 256 bits - is it dangerous to do an implementation outside of the standard?
hunter: r.e. the other code that's assuming things about the key length: I was looking at things like line 264: if( Nk > 6 && idx % Nk == 4 ). I understand what it's doing for standard values for Nk (where Nk is the number of 32-bit words in the key), but it's clearly not just the obvious extension of AES for longer keys.
Dec
19
comment tower of extension field
Your twisted curve is over $q^6$, no? So a point on it would be expressed in the form ((a,b),(c,d),(e,f)), ((g,h),(i,j),(k,l)). (That is, an (x,y) pair of triplets of pairs). The function that maps a point on the twist curve to the point on the normal curve over $q^{12}$ is the group homomorphism. The homomorphism in the paper above is (x,y) -> (ω²x, ω^3y), but yours may vary.
Dec
19
comment AES key length greater than 256 bits - is it dangerous to do an implementation outside of the standard?
Via that link, on line 251 (code.google.com/p/as3crypto/source/browse/trunk/as3crypto/src/…) the code is setting the number of rounds based on the size of the key. There is other logic in that function that assumes a standard key length. I think that fact that it doesn't check the key length is a bug and, by using a non-standard one, you're using a custom variant of AES that has never been studied.