Using SHA1 as RNG
Klaus Alexander Seistrup
spam at magnetic-ink.dk
Fri Mar 14 15:03:25 EST 2003
Giovanni Bajo wrote:
> Python 2.3 will use the Marsenne-Twister RNG, whose period is
> 2^19937-1. Big enough I'd say. It's also faster to calculate.
Thanks for bringing the good news. Yes, 2^19937-1 it big enough
for me. :)
>> So I thought, why not use SHA1 in the core generator?
>
> Unless you studied the distribution, you have no proof that the
> resulting sequence has a long period, for any starting seed.
Yes, you are right. Irmen de Jong also pointed out this serious
flaw.
> And besides, it would probably be very slow.
It's not too bad, as the SHA1 modules is written in C. However,
since I don't know anything about the distribution of numbers
within a SHA1 sequence, I'm probably better off waiting for the
Mersenne Twister to reach my Python interpreter.
Thanks for your feedback.
// Klaus
--
><> unselfish actions pay back better
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