Author: Dieter Buerssner
Date: 13:16:53 10/28/03
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On October 28, 2003 at 15:46:27, Dan Andersson wrote: > There is one supposedly 'very' secure and simple random generator that I like >because of its simplicity and randomness. The only assumption made is that >factoring large integers is 'hard'. The Blum Blum Shub: > Xn+1 = (Xn)2 mod M where M is a product of two large primes. The O(log log >M) least significant bits are random. You can also use relatively low values for >M and use the parity of Xn as output for one bit at a time if large values are >unworkable. I am not too convinced, yet. Can you show a sample implementation here (preferably one, that does have M < 2**64 - I am not interested in cryptographic use, just like to test the randomness of the output). I guess, I can implement it myself easily, when you can suggest a suitable M. Perhaps you would also know the cycle-length. The cycle length clearly <= M. So, I fear, it is possible, that it may fail known statistical tests on the randomness for even rather large values of M. For intermediate values (say around 2**63) one might already get a "feeling" about its behaviour. > It is not fast by any means ;) It should be more than fast enough for chess engines. It might be fast enough for some serious simulations. Regards, Dieter
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