On Mon, Nov 23, 2015 at 05:56:01AM +0000, Alistair G. Crooks wrote:
> Module Name: othersrc
> Committed By: agc
> Date: Mon Nov 23 05:56:01 UTC 2015
>
> Update of /cvsroot/othersrc/external/bsd/ibbs
> In directory ivanova.netbsd.org:/tmp/cvs-serv12751
>
> Log Message:
> Import an integer-based version of the Blum Blum Shub random number
> generator into othersrc.
>
> IBBS - Integer Blum Blum Shub Random Number Generator
> =====================================================
>
> This is a small Blum Blum Shub implementation which uses a Mersenne
> Twister to take 4 bytes of entropy (retrieved from the microseconds
> part of gettimeofday(2)), and generates 2 prime numbers and a seed from
> this. Each prime number and seed is 16 bits. A deterministic prime
> check is used to ensure we are dealing with safe/unsafe prime numbers.
>
> Since 16 bits are used for the two primes, care is taken to avoid
> cycles in the BBS output. If a cycle is detected, the generator is
> re-seeded, and output starts again.
>
> The RNG seems to be quite efficient, generating numbers at 10 MBps
> on a NetBSD VM running in Fusion hosted on Mac OS X.
Doesn't sound like anywhere near enough entropy.
If you start with 32 bits you'll get 'birthday paradox' duplicated
sequences after a relatively small number of boots.
David
--
David Laight: da...@l8s.co.uk
