/dev/random question

[Roland Smith]

On Thu, Sep 13, 2007 at 05:31:55PM +0100, RW wrote:
> On Thu, 13 Sep 2007 17:36:30 +0200
> Roland Smith <rsmith at xs4all.nl> wrote:
> 
> > On Thu, Sep 13, 2007 at 04:56:26PM +0200, Per olof Ljungmark wrote:
> > > Hi,
> > > 
> > > Could someone on the list point me to a document that explains the 
> > > functionality of /dev/random in FreeBSD in a little more depth than
> > > the man page? In other OS's I've looked at random and urandom are
> > > different, here it's a symlink (talking about RELENG-6 onwards).
> >  
> > FreeBSD uses the yarrow algorithm, as mentioned in random(4). See 
> > http://en.wikipedia.org/wiki/Yarrow_algorithm
> > http://www.schneier.com/yarrow.html
> 
> Yarrow is reseeded with interrupt entropy, and is supposedly good
> enough not to require the amount of entropy to be tracked.
> So /dev/random need not block, and there's no need for a separate
> non-blocking device.  

On the website it says that the original yarrow algorithm is no longer
supported. It seems to have been replaced by the fortuna algorithm.

I can't see from the source if /usr/src/sys/dev/random/yarrow.* use the
original yarrow algorithm, or the improved yarrow-160 aka fortuna. The use of
crypto/rijndael/rijndael-api-fst.h and crypto/sha2/sha2.h seem to
indicate the latter though.

Roland
-- 
R.F.Smith                                   http://www.xs4all.nl/~rsmith/
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