Investigations of cellular automata-based stream ciphers

In this thesis paper, we survey the literature arising from Stephan Wolfram\u27s original paper, “Cryptography with Cellular Automata” [WOL86] that first suggested stream ciphers could be constructed with cellular automata. All published research directly and indirectly quoting this paper are summarized up until the present. We also present a novel stream cipher design called Sum4 that is shown to have good randomness properties and resistance to approximation using linear finite shift registers. Sum4 is further studied to determine its effective strength with respect to key size given that an attack with a SAT solver is more efficient than a bruteforce attack. Lastly, we give ideas for further research into improving the Sum4 cipher

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

© 1993, Springer Verlag. All rights reserved. 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.status: publishe