Re: Determenistic seeding of LuaJIT PRNG from C code
- From: Konstantin Olkhovskiy <lupus@xxxxxxxxxx>
- To: luajit <luajit@xxxxxxxxxxxxx>
- Date: Thu, 27 Mar 2014 21:15:44 +0400
2014-03-27 15:25 GMT+04:00 Mike Pall <mike-1403@xxxxxxxxxx>:
> Nope, that operation is completely predictable.
>
Cool, thanks!
> Ok, so it throws away a couple of bits, of course. But then ...
> there's no guarantee that different seeds will generate a
> different sequence, anyway.
>
I believe that probability of getting same sequences from different
high-quality pseudo random seeds must be low. Or I do not know
something about PRNG used in LuaJIT?
> For your use case it might be best to use a dedicated PRNG that
> isn't global like math.random(). Then you have full control over
> the seeding process etc. Most PRNGs can be implemented quite
> efficiently with the FFI and the 64 bit bit operations available
> in LuaJIT 2.1. Or you could just call an existing C implementation
> via the FFI.
>
We have a sandboxed execution environment and client code can not
call math.randomseed directly.
I decided to use LuaJIT's PRNG because it's simple and my tests indicate
that it's determenistic, when seeded from 64bit integer.
We can later on switch to custom PRNG if the needed.
Thanks for your help, Mike!
--
Regards,
Konstantin
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