LAUSR

In this paper, we propose a method of efficient software implementation for the cryptographic hash function LSH with single instruction multiple data (SIMD). The method is based on word-wise permutations of LSH. Using the modified functions $Step'_{j}=P \circ Step_{j} \circ P^{-1}$ and $MsgExp'$ instead of the original step function $Step_{j}$ and message expansion function $MsgExp$ , where $P$ is a permutation and $P^{-1}$ is the inverse permutation of $P$ , we show that the number of the SIMD instructions for implementing LSH is reduced. For efficient implementation of LSH in other environments (e.g., MIMD), various types of word permutations are listed.