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Erschienen in:
2011 | OriginalPaper | Buchkapitel
MJH: A Faster Alternative to MDC-2
verfasst von : Jooyoung Lee, Martijn Stam
Erschienen in: Topics in Cryptology – CT-RSA 2011
Verlag: Springer Berlin Heidelberg
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In this paper, we introduce a new class of double-block-length hash functions. In the ideal cipher model (for
n
-bit blocks), we prove that these hash functions, dubbed MJH, are provably collision resistant up to
$O(2^{\frac{2n}{3}-\log n})$
queries in the iteration.
When based on
n
-bit key blockciphers, our construction 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 2
n
-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, at the expense of (for the moment) reduced provable security.