A framework for the design of one-way hash functions including cryptanalysis of damgård's one-way function based on a cellular automaton

Abstract

At Crypto '89 Ivan Damgård [1] presented a method that allows one to construct a computationally collision free hash function that has provably the same level of security as the computationally collision free function with input of constant length that it is based upon. He also gave three examples of collision free functions to use in this construction. For two of these examples collisions have been found [2]. [3], and the third one is attacked in this paper. Furthermore it is argued that his construction and proof, in spite of their theoretical importance, encourage inefficient designs in the case of practical hash functions. A framework is presented for the direct design of collision free hash functions. Finally a concrete proposal is presented named Cellhash.