Date: Mon, 12 Apr 2004 20:44:49 -0400 From: Richard Coleman <richardcoleman@mindspring.com> To: Nate Lawson <nate@root.org> Cc: Mark Murray <mark@grondar.org> Subject: Re: cvs commit: src/sys/modules/random Makefile src/sys/dev/random randomdev.h randomdev_soft.c randomdev_soft.h yar Message-ID: <407B3801.4090001@mindspring.com> In-Reply-To: <20040412153153.I70759@root.org> References: <200404110746.i3B7kiIn075106@grimreaper.grondar.org> <20040412153153.I70759@root.org>
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Nate Lawson wrote: >>Yarrow's entropy accumulation and PRNG generator parts are disconnected >>(that is part of its point), so there is no connection between the >>number of bytes harvested and the number of bytes supplied. This >>makes a very long armoured pipeline between accumulation and issue, >>which seems like overkill when the suppied entropy is 99% OK (far >>better than Yarrow currently ever gets, BTW). >> >>[...] >> >>Yarrow is unsuitable for this purpose; it is a great generator when >>you have a low-entropy environment and you need to protect against >>attackers having potential knowledge of the inputs. > > > * XSTORE is an unprivileged operation, users can call it all they want. > > * If your hardware fails undetectably somehow (101010101...), a > single-source PRNG also fails. If we seed our existing PRNG which > accepts multiple sources, it doesn't. > > I think Jacques said it best. All I'm asking is that we use a > well-reviewed PRNG and as many entropy sources as possible, including this > nice VIA part. > > -Nate I agree with this sentiment. The more crypto hardware that becomes available, the more of it that will be crap. Now, the obvious question is what post-processing does OpenBSD do to hardware random number generators? I read the semi-recent paper on the crypto framework for OpenBSD (http://www.openbsd.org/papers/ocf.pdf) but it doesn't mention anything about this. Anyone know offhand? Richard Coleman richardcoleman@mindspring.com
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