Improved preimage attacks against reduced HAS-160

Abstract

HAS-160 is a Korean industry standard for hash functions. It has a similar structure to SHA-1 and produces a 160-bit hash value. In this paper, we propose improved preimage attacks against step-reduced HAS-160 using the differential meet-in-the-middle technique and initial structure. Our work finds a pseudo-preimage of 70 steps of HAS-160 with a complexity of 2155.71 and this pseudo-preimage attack can be converted to a preimage attack with a complexity of 2158.86. Moreover, we reduce the complexity of previous pseudo-preimage attack on 65-step HAS-160 from 2143.4 to 2 139.09. To the best of our knowledge, our result on 70 steps is the best preimage attack on HAS-160 in terms of attacked steps © 2014 Springer International Publishing.