From: George Spelvin <lkml@sdf.org>
To: lkml@sdf.org, stephen@networkplumber.org
Cc: daniel@iogearbox.net, hannes@stressinduktion.org, netdev@vger.kernel.org
Subject: Re: Revising prandom_32 generator
Date: Tue, 26 Mar 2019 16:24:59 GMT [thread overview]
Message-ID: <201903261624.x2QGOxOV006525@sdf.org> (raw)
In-Reply-To: <20190326075839.5a94442b@shemminger-XPS-13-9360>
> A little backstory. I started the prandom_32 stuff long ago when I wanted
> a better (longer period) PRNG for use in netem. Took the existing code from
> older version of GNU scientific library (pre GPLv3). If there is something
> faster with better properties go for it. But the whole point of prandom_32
> is that it doesn't have to be crypto quality.
Than you for the encouragement! The lfsr113 generator is really
a perfectly respectable generator. There's nothing about it that
"needs fixing"; it's just possible to do slighty better.
When I can get better statistics, longer period (for the same state
size), faster *and* smaller code size, it seems worth looking into.
And yes, I understand "pseudorandom" very well. From a documentation
patch for drivers/char/random.c I also posted recenty:
+ *
+ * prandom_u32()
+ * -------------
+ *
+ * For even weaker applications, see the pseudorandom generator
+ * prandom_u32(), prandom_max(), and prandom_bytes(). If the random
+ * numbers aren't security-critical at all, these are *far* cheaper.
+ * Useful for self-tests, random error simulation, randomized backoffs,
+ * and any other application where you trust that nobody is trying to
+ * maliciously mess with you by guessing the "random" numbers.
prev parent reply other threads:[~2019-03-26 16:25 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-26 11:10 Revising prandom_32 generator George Spelvin
2019-03-26 11:17 ` George Spelvin
2019-03-26 18:03 ` Hannes Frederic Sowa
2019-03-26 19:07 ` George Spelvin
2019-03-26 19:23 ` Stephen Hemminger
2019-03-27 18:32 ` Hannes Frederic Sowa
2019-03-27 21:43 ` George Spelvin
2019-03-26 14:58 ` Stephen Hemminger
2019-03-26 16:24 ` George Spelvin [this message]
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