On the universal hash functions in Luby-Rackoff cipher
It is known that a super-pseudorandom permutation on 2n bits can be obtained from a random function f on n bits and two bi-symmetric and AXU hash functions h(1) and h(2) on n bits. It has a Feistel type structure which is usually denoted by phi(h(1), f, f, h(2)). Bi-symmetric and AXU hash functions h(1), h(2) are much weaker primitives than a random function f and they can be computed much faster than random functions. This paper shows that we can further weaken the condition on h(1).
super-pseudorandomness cryptography block cipher feistel permutation