On Tue, 2005-03-29 at 20:46 +1000, Herbert Xu wrote: > On Tue, Mar 29, 2005 at 02:50:28PM +0400, Evgeniy Polyakov wrote: > > > > Without ability speed this up in kernel, we completely [ok, almost] > > loose all RNG advantages. > > Well if you can demonstrate that you're getting a higher rate of > throughput from your RNG by doing this in kernel space vs. doing > it in user space please let me know.
Quote from VIA RNG crypto analysis:
"Bitrate. The RNG generates output at significantly
higher rates than most PC-based randomness resources.
Raw bits are produced at rates of 30 to 50 Mbits/sec,
and whitened bits were observed at rates of 4 to 9
Mbits/sec. Variations in output rates depend on the
RNG configuration and the oscillator rates. PRNGs
seeded with the Nehemiah RNG should be able to
easily sustain output in excess of 2 Mbits of entropy per
second, which should eliminate blocked PRNG reads in
virtually all applications."
While raw bits reading from hw_random on the fastest
VIA boards can exceed 55mbits per second
[above quite was taken from VIA C3 Nehemiah analysis],
it is not evaluated in rngd and is not written
back to the /dev/random.
David provided his patch exactly because of
"Adding this can dramatically improve the performance of
/dev/random on small embedded systems which do not
generate much entropy."
and it works.
--
Evgeniy Polyakov
Crash is better than data corruption -- Arthur Grabowski
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