## Cryptology ePrint Archive: Report 2012/633

New Preimage Attack on MDC-4

Deukjo Hong and Daesung Kwon

Abstract: In this paper, we provide some cryptanalytic results for double-block-length (DBL) hash modes of block ciphers, MDC-4. Our preimage attacks follow the framework of Knudsen et al.'s time/memory trade-off preimage attack on MDC-2. We find how to apply it to our objects. When the block length of the underlying block cipher is $n$ bits, the most efficient preimage attack on MDC-4 requires time and space about $2^{3n/2}$, which is to be compared to the previous best known preimage attack having time complexity of $2^{7n/4}$. Additionally, we propose an enhanced version of MDC-4, MDC-4$^*$ based on a simple idea. It is secure against our preimage attack and previous attacks and has the same efficiency as MDC-4.

Category / Keywords: MDC-4, Hash Function, Preimage

Date: received 6 Nov 2012, last revised 12 Nov 2012

Contact author: hongdj at ensec re kr

Available format(s): PDF | BibTeX Citation

Note: A typo in reference is corrected.

Short URL: ia.cr/2012/633

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