Paper 2012/634

Cryptanalysis of Double-Block-Length Hash Mode MJH

Deukjo Hong and Daesung Kwon

Abstract

A double-block-length (DBL) hash mode of block ciphers, MJH has been proved to be collision-resistant in the ideal cipher model upto $2^{2n/3- \log n}$ queries. In this paper we provide first cryptanalytic results for MJH. We show that a collision attack on MJH has the time complexity below the birthday bound. When block ciphers with 128-bit blocks are used, it has time complexity around $2^{124}$, which is to be compared to the birthday attack having complexity $2^{128}$. We also give a preimage attack on MJH. It has the time complexity of $2^{3n/2+1}$ with $n$-bit block ciphers, which is to be compared to the brute force attack having complexity $2^{2n}$.

Metadata
Available format(s)
PDF
Category
Secret-key cryptography
Publication info
Published elsewhere. Unknown where it was published
Keywords
MJHHash FunctionCollisionPreimage
Contact author(s)
hongdj @ ensec re kr
History
2012-11-11: received
Short URL
https://ia.cr/2012/634
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2012/634,
      author = {Deukjo Hong and Daesung Kwon},
      title = {Cryptanalysis of Double-Block-Length Hash Mode MJH},
      howpublished = {Cryptology ePrint Archive, Paper 2012/634},
      year = {2012},
      note = {\url{https://eprint.iacr.org/2012/634}},
      url = {https://eprint.iacr.org/2012/634}
}
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