Cryptology ePrint Archive: Report 2007/465

A Synthetic Indifferentiability Analysis of Some Block-Cipher-Based Hash Functions

Zheng Gong and Xuejia Lai and Kefei Chen

Abstract: At \textsl{ASIACRYPT'06}, Chang \textit{et al}. analyzed the indifferentiability of some popular hash functions based on block-cipher namely, the 20 collision resistant PGV hash functions, the MDC2 and the PBGV etc. In particular, two indifferentiable attacks were shown on the 4 of the 20 collision resistant PGV hash functions and the PBGV with the prefix-free padding. In this article, a synthetic indifferentiability analysis of some block-cipher-based hash functions is considered. First, a more precise definition is proposed on the adversary in block-cipher-based hash functions. Next, the advantage of indifferentiability is extended by considering whether the hash function is keyed or not. Finally, a limitation is observed in Chang et al.'s indifferentiable attacks on the four PGV hash functions and the PBGV. In particular, the formal proofs prove those hash functions are indifferentiable from random oracle in the ideal cipher model with the prefix-free padding, the NMAC/HMAC and the chop construction.

Category / Keywords: foundations / Hash Function, Block Cipher, Indifferentiability, Random Oracle

Publication Info: under a journal's review

Date: received 11 Dec 2007, last revised 20 Mar 2008

Contact author: neoyan at sjtu edu cn

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Version: 20080320:135949 (All versions of this report)

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