The Pseudorandomness of Elastic Block Ciphers

Cook, Debra L.; Yung, Moti; Keromytis, Angelos D.

We investigate elastic block ciphers, a method for constructing variable length block ciphers, from a theorectical perspective. We view the underlying structure of an elastic block cipher as a network, which we refer to as an elastic network, and analyze the network in a manner similar to the analysis performed by Luby and Rackoff on Fesitel networks. We prove that a three round elastic network is a pseudorandom permutation and a four round network is a strong pseudorandom permutation when the round functions are pseudorandom permutations.



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Academic Units
Computer Science
Department of Computer Science, Columbia University
Columbia University Computer Science Technical Reports, CUCS-037-05
Published Here
April 21, 2011