PCG, A Family of Better Random Number Generators

Re:PCG, A Family of Better Random Number Generators by daurnimator on Wednesday July 15, 2015 @02:51AM (#9890060)

> Just as you wouldn't want to use a general purpose PRNG for security applications so too you wouldn't want to use a secure PRNG for general purposes, particularly demanding applications such as Monte Carlo simulations.

Why not? It's perfectly valid to use a secure RNG for non-secure purposes.

As I mentioned, I've used ChaCha20 for those sort of purposes too. And the random number generation barely shows up as a fraction of the runtime.

i.e. improving 1% of the runtime by 99% isn't worth the overhead of having more than one random number generator.

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Re:PCG, A Family of Better Random Number Generators by danieltillett on Wednesday July 15, 2015 @04:12AM (#9890257)

The reason why is crypto RNG are much slower than something less secure. It really depends on the application, but in the code I wrote today a significant fraction of my application’s time was spent in the RNG function. By replacing the RNG I managed to speed up my code by a bit over 2 fold. I am not doing crypto work so this is great.

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Re:PCG, A Family of Better Random Number Generators by daurnimator on Wednesday July 15, 2015 @09:56PM (#9895136)

ChaCha is fast. very fast. see just below: https://news.ycombinator.com/item?id=9890599 I'm not sure why they marked it as "fairly slow" in the table in the OP.

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Re:PCG, A Family of Better Random Number Generators by danieltillett on Thursday July 16, 2015 @09:20AM (#9896953)

Fast and slow are all relative - ChaCha is relatively fast but PGC is faster.

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Re:PCG, A Family of Better Random Number Generators by ars on Wednesday July 15, 2015 @04:19AM (#9890270)

> Why not? It's perfectly valid to use a secure RNG for non-secure purposes.

It's much slower. Yes, in your application it was a fraction, but they are still much slower than non-secure RNG's.

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Re:PCG, A Family of Better Random Number Generators by eterm on Wednesday July 15, 2015 @04:23AM (#9890283)

One of the benefits of a PRNG is reproducibility. If you are doing a monte carlo simulation, then you can get good results while still starting runs from predictable seeds. (e.g. [0,1,2,3,4,...])

This gives you both good quality random numbers during the simulation run yet lets others reproduce your results and expand with more results if required.

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Re:PCG, A Family of Better Random Number Generators by dchest on Wednesday July 15, 2015 @04:30AM (#9890298)

ChaCha20 is a cipher, of course, it creates reproducible sequences.

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