## Cryptology ePrint Archive: Report 2008/109

Collisions for Round-Reduced LAKE

Florian Mendel and Martin Schläffer

Abstract: LAKE is a family of cryptographic hash functions presented at FSE 2008. It is an iterated hash function and defines two main instances with a 256 bit and 512 bit hash value. In this paper, we present the first security analysis of LAKE. We show how collision attacks, exploiting the non-bijectiveness of the internal compression function of LAKE, can be mounted on reduced variants of LAKE. We show an efficient attack on the 256 bit hash function LAKE-256 reduced to 3 rounds and present an actual colliding message pair. Furthermore, we present a theoretical attack on LAKE-256 reduced to 4 rounds with a complexity of $2^{109}$. By using more sophisticated message modification techniques we expect that the attack can be extended to 5 rounds. However, for the moment our approach does not appear to be applicable to the full LAKE-256 hash function (with all 8 rounds).

Category / Keywords: cryptanalysis, hash functions, collision attack

Publication Info: The final version of this paper has been published at ACISP 2008.

Date: received 11 Mar 2008, last revised 14 Aug 2008

Contact author: martin schlaeffer at iaik tugraz at

Available format(s): PDF | BibTeX Citation