sbox hacking [power functions]

Interesting paper at

http://eprint.iacr.org/2006/322

About the bi-affine and quadratic nature of various power mapping
functions. They generalize construction techniques to prove that you
can construct non-bijective and bijective functions with no bi-affine
solutions and independently create sboxes with no [iirc] quadratic
solutions [or useful ones at least].

Anyways, interesting read, especially since sbox design is still not
100% solid.

Tom

.