First European Symposium On Research In Computer Security (ESORICS 90)
Pseudorandom Permutations Based on the D.E.S. Scheme
Jacques Patarin
Keywords : Cryptology, D.E.S., Psudorandom generators
Abstract : We will mainly present the results exposed by Michel Luby and Charles Rackoff in "How to construct pseudorandom permutations from pseudorandom functions", SIAM J. Comput., 1988, and the new results on that subject. No demonstrations will be given here but in an article for Eurocode 90, I will give a complete proof of the main results. (This proof will be sensibly simpler and more complete than the one given by Luby and Rackoff). The two main results are: 1. A three iteration DES scheme where the S-boxes are replaced by random functions (or by a pseudo-random function generator) will give us an invertible pseudorandom function generator. That is to say a cryptosystem which is secure against chose plaintext attacks. 2. A four (or more) iterations DES Scheme where the S-boxes are replaced by random functions (or by a pseudorandom function generator) will give us an invertible super pseudorandom permutation generator. That is to say a cryptosystem which is secure againts chose plaintext and chosen ciphertext attacks.
(Pages 185-187)