Cryptology ePrint Archive: Report 2014/108

MJH: A Faster Alternative to MDC-2

Jooyoung Lee and Martijn Stam

Abstract: In this paper, we introduce a new class of double-block-length hash functions. Using the ideal cipher model, we prove that these hash functions, dubbed \MJH, are asymptotically collision resistant up to $O(2^{n(1-\epsilon)})$ query complexity for any $\epsilon>0$ in the iteration, where $n$ is the block size of the underlying blockcipher.

When based on $n$-bit key blockciphers, our construction, being of rate 1/2, provides better provable security than MDC-2, the only known construction of a rate-1/2 double-length hash function based on an $n$-bit key blockcipher with non-trivial provable security. Moreover, since key scheduling is performed only once per message block for MJH, our proposal significantly outperforms MDC-2 in efficiency.

When based on a $2n$-bit key blockcipher, we can use the extra $n$ bits of key to increase the amount of payload accordingly. Thus we get a rate-1 hash function that is much faster than existing proposals, such as Tandem-DM with comparable provable security. The proceedings version of this paper appeared in CT-RSA 2011.

Category / Keywords: secret-key cryptography / hash function, blockcipher, provable security, collision resistance

Original Publication (in the same form): DESIGNS, CODES AND CRYPTOGRAPHY

Date: received 12 Feb 2014

Contact author: jlee05 at sejong ac kr

Available format(s): PDF | BibTeX Citation

Version: 20140215:214107 (All versions of this report)

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