MJH: A Faster Alternative to MDC-2

Abstract

AbstractIn 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 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, at the expense of (for the moment) reduced provable security.KeywordsHash FunctionBlock CipherCompression FunctionMessage BlockProvable SecurityThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.