Splittable random numbers

[Thomas DuBuisson]

On Thu, Nov 4, 2010 at 11:25 AM, Ian Lynagh <igloo at earth.li> wrote:
> On Thu, Nov 04, 2010 at 05:38:12PM +0000, Simon Peyton-Jones wrote:
>>
>> The generator uses crypto functions,
>
> Does that mean it couldn't be used in some countries?

IANAL, but the restrictions can be extremely specific.  For example,
some software used hash based mixing algorithms instead of cipher
based ones which was sufficient to work around this issue in the
important cases.

> I wonder if you can make a splittable generator that uses crypto
> functions when you split it, but is a common linear-sequence generator
> otherwise?

Before we bother to do that I think it would be worth deciding what
level of performance we are trying to achieve.  On my laptop (Core2
2.5Ghz) I generate 4MB of random values in less than 900ms (HashDRBG).
 What is StdGen getting, which I know people consider slow?  Also, how
much do we care about the splitting speed?

Cheers,
Thomas