cvs commit: src/sys/modules/random Makefile src/sys/dev/random harvest.c hash.c hash.h nehemiah.c nehemiah.h probe.c randomdev.c randomdev.h randomdev_soft.c randomdev_soft.h yar

Mark Murray mark at
Sun Apr 11 01:40:12 PDT 2004

Nate Lawson writes:
> > Cryptographic strength is of lesser importance here, as the key
> > input is Very Nicely Random(tm), however AES's speed and spectral
> > qualities make it a good choice. It is important to remember that
> > the hash is purely there to destroy any trends/tendencies that the
> > hardware generator may have, and for that purpose an LFSR may work
> > just fine. The hash is a "Whitener", and its requirements here are
> > that its output spectrum is flat.
> An LFSR is not a cryptographic hash function.  Do not use one to implement
> a PRNG.

The input is 99% random. It follows that if the hash/whitener is done properly
the output should be 99% random.

LFSR was an illustration; the intent is to use AES.

Mark Murray
iumop ap!sdn w,I idlaH

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