Linear Hybrid Cellular Automata: https://pdfs.semanticscholar.org/7835/161f253ab117a3666fa8e7...

Parallelizable and efficient method for producing high quality pseudo random bits.

Designed to achieve maximal period (with 500 bit state the period of repetition is one less than 2^500).

Can be run backwards or forwards. Running it backwards undoes running it forwards and reproduces the pseudo random bits in reverse order.