Messages in this thread |  | | Date | Mon, 19 Aug 2002 10:29:36 -0500 | From | Oliver Xymoron <> | Subject | Re: Problem with random.c and PPC |
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On Mon, Aug 19, 2002 at 05:11:03PM +0200, Marco Colombo wrote: > On Mon, 19 Aug 2002, Oliver Xymoron wrote: > > > > If you need a weak solution (a perturbated PRNG), just read a few bits > > > from /dev/random at times (but in a controlled and defined way). > > > > It might be helpful to think of /dev/urandom as akin to /dev/random with > > O_NONBLOCK. "Give me stronger bits if you got 'em" is desirable, > > otherwise this thread would be much shorter. > > "desirable", yes, I see... B-). But I have to understand why, yet. > > "Give me the best you can, but even 0 is ok" just serves to help people > waste resources. If your application is fine with (potentially) > guessable bits, you don't need /dev/random at all. If you do care > about a minimum, you know it in advance, so do fetch those bits > (and only them) from /dev/random, and use them. Yes, it may block, > but that's life. Resources aren't infinite.
For most people, entropy input far exceeds entropy output and the pool is a finite size. There's no reason not to use these entropy bits as the pool is always full and we're discarding entropy constantly. It's only a problem when the pool is running low and we risk making /dev/random block.
> I'm missing any real argument for having /dev/urandom logic into the > kernel.
Convenience and control of resource sharing. The latter is slightly under-implemented.
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