Re: [RFC] frandom - fast random generator module

[jw schultz <jw@pegasys.ws>]

On Fri, Oct 17, 2003 at 01:03:26AM +0200, Eli Billauer wrote:
> Matt Mackall wrote:
> 
> >On Thu, Oct 16, 2003 at 07:29:05AM -0400, Jeff Garzik wrote:
> > 
> >
> >>So, given that trend and also given the existing /dev/[u]random, I 
> >>disagree completely:  /dev/frandom is the perfect example of something 
> >>that should _not_ be in the kernel.  If you want /dev/urandom faster, 
> >>then solve _that_ problem.  Don't try to solve a /dev/urandom problem by 
> >>creating something totally new.
> >>   
> >>
> >
> >I have some performance fixes for /dev/urandom, but there's a fair
> >amount of other cleanup that has to go in first.
> >
> ... and this reminded me that I originally wanted to patch random.c, and 
> change the algorithm to the faster one. To my best understanding, there 
> would be no degradation in random quality, assuming I would do it 
> correctly (and not being hung for the nerve to do it). But that's the 
> problem: What if I got something wrong?
> 
> If a hardware device driver is buggy, you usually know about it sooner 
> or later. If an RNG has a rare bug, or an architecture-dependent flaw, 
> it's much harder to notice. If the RNG starts to repeat itself, you 
> won't know about it, unless you happened to test exactly that data. The 
> algorithm may be perfect, but a silly bug can blow it all.
> 
> So personally, I wouldn't touch the urandom code, not even the smallest 
> fix. Instead, I decided to write another RNG, which doesn't interfere 
> with the existing one. The only way to be confident about it, is to give 
> it mileage. And that means making it available for broad use.
> 
> Which is why I originally offered frandom as a supplement, not an 
> alternative.

Sounds like a case for having a config choice for which
urandom code to build in.

-- 
________________________________________________________________
	J.W. Schultz            Pegasystems Technologies
	email address:		jw@pegasys.ws

		Remember Cernan and Schmitt