Cryptology ePrint Archive: Report 2007/347
Lai-Massey Scheme and Quasi-Feistel Networks
Aaram Yun and Je Hong Park and Jooyoung Lee
Abstract: We introduce the notion of quasi-Feistel network, which is generalization of the Feistel network, and contains the Lai-Massey scheme as an instance. We show that some of the works on the Feistel network, including the works of Luby-Rackoff, Patarin, Naor-Reingold and Piret, can be naturally extended to our setting. This gives a new proof for theorems of Vaudenay on the security of the Lai-Massey scheme, and also introduces for Lai-Massey a new construction of pseudorandom permutation, analoguous to the construction of Naor-Reingold using pairwise independent permutations.
Also, we prove the birthday security of $(2b-1)$- and $(3b-2)$-round unbalanced quasi-Feistel networks with b branches against CPA and CPCA attacks, respectively. This answers an unsolved problem pointed out by Patarin et al.
Category / Keywords: foundations / Lai-Massey scheme, Feistel network, Luby-Rackoff, block cipher design, pseudorandom function, indistinguishability
Date: received 4 Sep 2007
Contact author: aaramyun at gmail com
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Version: 20070905:070201 (All versions of this report)
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