Cryptology ePrint Archive: Report 2013/607

Cryptanalysis of Full RIPEMD-128

Franck Landelle and Thomas Peyrin

Abstract: In this article we propose a new cryptanalysis method for double-branch hash functions that we apply on the standard RIPEMD-128, greatly improving over know results. Namely, we were able to build a very good differential path by placing one non-linear differential part in each computation branch of the RIPEMD-128 compression function, but not necessarily in the early steps. In order to handle the low differential probability induced by the non-linear part located in later steps, we propose a new method for using the freedom degrees, by attacking each branch separately and then merging them with free message blocks. Overall, we present the first collision attack on the full RIPEMD-128 compression function as well as the first distinguisher on the full RIPEMD-128 hash function. Experiments on reduced number of rounds were conducted, confirming our reasoning and complexity analysis. Our results show that 16 years old RIPEMD-128, one of the last unbroken primitives belonging to the MD-SHA family, might not be as secure as originally thought.

Category / Keywords: secret-key cryptography / RIPEMD-128, collision, distinguisher, compression function, hash function.

Original Publication (with minor differences): IACR-EUROCRYPT-2013

Date: received 19 Sep 2013

Contact author: thomas peyrin at gmail com

Available format(s): PDF | BibTeX Citation

Version: 20130923:033811 (All versions of this report)

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