Blum Blum Shub Pseudo Random Number Generator Coffeescript Implementation

This weekend hasn’t been as busy as they have been lately, so I’ve had a lot more time to just sit around. I was reading some articles on PRNGs, and a PRNG I’ve never heard of caught my eye. Mainly, I think, because of its name. Blum Blum Shub is a PRNG devised by some mathematicians and computer scientists in the mid 1980’s. I decided to do a Coffeescript implementation of it.

# An implementation of assert. AssertException = (message) -> @message = message assert = (exp, message) -> throw new AssertException(message) unless exp AssertException::toString = -> "AssertException: " + @message # Implementation of Blum Blum Shub # p - Large Prime 1. Should be congruent to 3 mod 4. # q - Large Prime 2. Should be to congruent to 3 mod 4. # s - The seed. Should be a co-prime of the product of p and q. blum_blum_shub = (p,q,s,i) -> # Primes p and q must be congruent to 3 mod 4 assert((p % 4) == 3, "Error: Prime P is not congruent to 3 mod 4") assert((q % 4) == 3, "Error: Prime Q is not congruent to 3 mod 4") m = p * q x = s for step in [0..i] x = (x * x) % m x

Sean Brewer

Blum Blum Shub Pseudo Random Number Generator Coffeescript Implementation

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