>At 10:33 PM 6/6/00 -0400, Arnold G. Reinhold wrote:
>> The patent ... claim[s] digitizing the state of any chaotic
>> system and then hashing it to seed a PRNG.
john kelsey replied:
> Wouldn't Don Davis' work on hard drive timings, in which
> he specifically claimed that the system was chaotic,
> qualify as prior art for this?
yes, well, there is that... .
but, when SGI announced their lavarand patent
application in the press a few years ago, i
decided that it wasn't worth worrying about.
theirs is clearly a defensive patent, intended
only to make sure that noone can keep SGI from
using anything they build around the idea of
hashing analog inputs. after all, sgi has
never tried to make linux stop using disk-
randomness in /dev/random. at the same time,
lavarand is clearly an insubstantial patent,
since my prior work was somewhat known even
before '94, when i published it. so i don't
see anything to worry about here.
ironically, when lavarand came out, i was working
on a disk-randomness pseudodev driver for irix.
it worked handsomely, but that's another story...
> [Wouldn't all the work done on things like hashing
> inputs in general to distil entropy, which was around
> for years before this patent, count? --Perry]
i'm sorry, but i don't agree; back then, the
idea of "hashing various inputs" had not been
well-justified as providing true entropy per se,
afaik. there was a "quasi-randomness" paper by
vazirani from around 1990, but that paper showed
only that biased i/o-derived bits could afford
a source of uniformly-distributed, pseudorandom
bits, whose prediction would cost more than
polynomial-time effort.
- don davis, boston
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