Cryptology ePrint Archive: Report 2007/223
On the Impossibility of Highly-Efficient Blockcipher-Based Hash Functions
John Black and Martin Cochran and Thomas Shrimpton
Abstract: Fix a small, non-empty set of blockcipher keys $K$. We say a blockcipher-based hash function is highly-efficient if it makes exactly one blockcipher call for each message block hashed, and all blockcipher calls use a key from $K$. Although a few highly-efficient constructions have been proposed, no one has been able to prove their security. In this paper we prove, in the ideal-cipher model, that it is impossible to construct a highly-efficient iterated blockcipher-based hash function that is provably secure. Our result implies, in particular, that the Tweakable Chain Hash (TCH) construction suggested by Liskov, Rivest, and Wagner is not correct under an instantiation suggested for this
construction, nor can TCH be correctly instantiated by any other efficient means.
Category / Keywords: blockciphers, hash functions
Publication Info: Previously appeared in the proceedings of Eurocrypt '05
Date: received 8 Jun 2007
Contact author: cochranm at colorado edu
Available format(s): Postscript (PS) | Compressed Postscript (PS.GZ) | PDF | BibTeX Citation
Note: This version fixes an error in the main proof of the paper published in Eurocrypt '05. That version incorrectly assumed that MD-strengthening does not affect the attack when more than one blockcipher key is used.
Version: 20070609:125148 (All versions of this report)
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