Chapter 10: Processes of Perception and Analysis

Section 10: Cryptography and Cryptanalysis

Directional sampling [in cellular automata]

One can consider sampling cells not in a vertical column but on lines at any angle. In a rule 30 system of infinite size, it turns out that at 45° clockwise from vertical all possible sequences can occur on any two adjacent lines, probably making cryptanalysis more difficult in this case. (Note that directional sampling is always equivalent to looking at a vertical column in the evolution of a cellular automaton whose basic rule has been composed with an appropriate shift rule.)

From Stephen Wolfram: A New Kind of Science [citation]