Collision Attack on the Hamsi-256 Compression Function

Abstract

Hamsi-256 is a cryptographic hash functions submitted by Küçük to the NIST SHA-3 competition in 2008. It was selected by NIST as one of the 14 round 2 candidates in 2009. Even though Hamsi-256 did not make it to the final round in 2010 it is still an interesting target for cryptanalysts. Since Hamsi-256 has been proposed, it received a great deal of cryptanalysis. Besides the second-preimage attacks on the hash function, most cryptanalysis focused on non-random properties of the compression function or output transformation of Hamsi-256. Interestingly, the collision resistance of the hash or compression function got much less attention. In this paper, we present a collision attack on the Hamsi-256 compression function with a complexity of about 2 124.1 .