Re: Need Suggestions for Random Numbers

From: Matthew J Ghio <mg5n+@andrew.cmu.edu> 1,1,2,3,5,8,13,21,34,55,89,144,233...

Taking modulo 10, we get:

1,1,2,3,5,8,3,1,4,5,9,4,3,7,0,7,7,4,1,5,6,1,7,8,5,3,8,1,9,0,9,9,8...

Which gives a fairly random distribution of numbers from 0 to 9.

This is a very simple linear congruential generator: a_n = a_n-1 + a_n-2 mod 10 It is decidedly *not* suitable for "producing an `acceptable' random file to be xor'd with the plaintext." It's not a cryptographically strong PRNG (it's not even a particularly good PRNG). To break such a system, try Boyar's paper, "Inferring Sequences Produced by PRNGs", in JACM 36(1): 129-141. I believe it takes time logarithmic in the modulus, which is not a recipe for security. Eli ebrandt@jarthur.claremont.edu