RNG (was: Re: SSD drives)

[E.S. Rosenberg]

I think xkcd summed it up very well for all those that are afraid of secret
services, you are the weakest link:
http://xkcd.com/538/


2013/1/6 Amos Shapira <amos.shapira at gmail.com>

> If someone is really concerned about NSA knowing their random seed through
> Intel's hardware implementation - can't these few people add hardware RNG's
> to their sources?
> (one ref:
> http://en.wikipedia.org/wiki/Comparison_of_hardware_random_number_generators
> )
>
>
> On 3 January 2013 11:42, Oleg Goldshmidt <pub at goldshmidt.org> wrote:
>
>> On Thu, Jan 3, 2013 at 1:50 PM, Nadav Har'El <nyh at math.technion.ac.il>
>> wrote:
>> > On Thu, Jan 03, 2013, Yedidyah Bar-David wrote about "RNG (was: Re: SSD
>> drives)":
>> >> RDRAND is also a PRNG, reseeded at most once every 1022 calls, way
>> >> faster than /dev/urandom (they state 500MiB per second), and you do not
>> >> have its source code...
>> >
>> > Can anyone give me an example of why on earth anyone would need a
>> > very high throughput random number generator?
>> >
>> > I can understand why things like monte-carlo simulations and ray tracing
>> > might need a lot of random numbers, but for them PRNG in the program
>> > (e.g., rand(3)) is perfectly fine
>>
>> It is absolutely lousy for any serious simulation work - it is
>> absolutely not random, and I know for a fact that in a serious Monte
>> Carlo it will give you wrong results where a good PRNG will give you
>> correct ones. In the past I tested many PRNGs on problems I knew the
>> answer for. The vast majority were rubbish. Those that were very
>> random (it was before NIST, so I relied on DIEHARD) gave good results.
>>
>> Actually, what is needed for simulations is uniform coverage of the
>> state space, not randomness, which is why low-discrepancy (a.k.a.
>> quasi-random) numbers work. Lousy PRNGs are not uniformly distributed
>> (when you plot them the problem can often be seen by the naked eye).
>> It leads to both lousy simulation results and weak cryptographic
>> properties. Suitability for simulations does not mean strong
>> cryptography.
>>
>> > for any of these super-duper super-secure generators in the kernel or
>> the CPU...
>>
>> It has to be very random. It has been demonstrated many times how easy
>> it is to exploit a not very random kernel RNG (guess TCP sequence
>> numbers and so on). Microsoft: looking at you.
>>
>> --
>> Oleg Goldshmidt | pub at goldshmidt.org
>>
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>
>
>
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