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Re: random numbers API

From: Florian Bösch <pyalot@gmail.com>
Date: Fri, 16 Nov 2012 18:20:41 +0100
Message-ID: <CAOK8ODj5addMb9FbaOsfXauN4wyj+Jxqz+CWJw9HfVEdrsmRFg@mail.gmail.com>
To: David Bruant <bruant.d@gmail.com>
Cc: Frederick.Hirsch@nokia.com, Webapps WG <public-webapps@w3.org>
I'll see that I can come up with a test suite that verifies statistical and
runtime behavior of an array of algorithms implemented in JS, it'll
probably take a while.


On Fri, Nov 16, 2012 at 6:02 PM, David Bruant <bruant.d@gmail.com> wrote:

>  Le 16/11/2012 17:35, Florian Bösch a écrit :
>
> On Fri, Nov 16, 2012 at 5:20 PM, David Bruant <bruant.d@gmail.com> wrote:
>
>>  That'd be a nonsense to add seeding in my opinion. If you want
>> security, you don't want to take the risk of people seeding and loose all
>> security property. If it's for debugging purposes, the seeding should be
>> part of a devtool, not of the web-facing API.
>>
> I agree that in the crypographic context seeding might not make sense (or
> even guarantees about repeatability).
>
>  The purpose of the proposal of a fast, reliable, statistically sound,
> repeatable, seedable PRNG in JS however is not to do cryptography. It would
> be to be able to perform procedural computation repeatably regardless of
> machine, VM, optimization and vendor differences. An example: Say you
> wanted to do a procedural universe consisting of 1 million stars. At 3
> cartesian coordinates per star and at each component having 8 bytes, you'd
> get 22MB of data. If you want to share this galaxy with anybody you'll have
> to pass them this 22mb blob. If you want multiple people in the same
> galaxy, you have to pass them that blob.
>
> If you want repeatable, you actually don't want random (as your title
> suggests) but PRNG very specifically ("pseudo" being themost important
> part). In that case, I feel writing your own PRNG will be almost as fast as
> a native one with nowadays crazy JIT. Just write an algorithm that you're
> satisfied and pass around the algo and any parametrization you want. I feel
> it would solve your use case.
>
>
>  It takes about 0.7 seconds in C to generate 3 million statistically
> sound random numbers for longs.
>
> Do you have measurements of how much the same algo takes in JS?
>
> David
>
Received on Friday, 16 November 2012 17:21:09 GMT

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