## Cryptology ePrint Archive: Report 2013/174

Cryptanalysis of Some Double-Block-Length Hash Modes of Block Ciphers with $n$-Bit Block and $n$-Bit Key

Deukjo Hong and Daesung Kwon

Abstract: In this paper, we make attacks on DBL (Double-Block-Length) hash modes of block ciphers with $n$-bit key and $n$-bit block. Our preimage attack on the hash function of MDC-4 scheme requires the time complexity $2^{3n/2}$, which is significantly improved compared to the previous results. Our collision attack on the hash function of MJH scheme has time complexity less than $2^{124}$ for $n = 128$. Our preimage attack on the compression function of MJH scheme find a preimage with time complexity of $2^n$. It is converted to a preimage attack on the hash function with time complexity of $2^{3n/2+2}$. Our preimage attack on the compression function of Mennink's scheme find a preimage with time complexity of $2^{3n/2}$. It is converted to a preimage attack on the hash function with time complexity of $2^{7n/4+1}$. These attacks are helpful for understanding the security of the hash modes together with their security proofs.

Category / Keywords: secret-key cryptography / Hash Function, Hash Mode, Collision, Preimage

Date: received 27 Mar 2013, last revised 5 Apr 2013

Contact author: hongdj at ensec re kr

Available format(s): PDF | BibTeX Citation

Note: Some of described attacks are revised.

Short URL: ia.cr/2013/174

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