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Date:      Tue, 30 Nov 1999 11:13:30 +0100
From:      Brad Knowles <blk@skynet.be>
To:        Dan Moschuk <dan@FreeBSD.ORG>
Cc:        Kris Kennaway <kris@hub.freebsd.org>, Dan Moschuk <dan@FreeBSD.ORG>, Bruce Evans <bde@zeta.org.au>, Mike Smith <msmith@FreeBSD.ORG>, audit@FreeBSD.ORG, Warner Losh <imp@village.org>
Subject:   Re: cvs commit: src/sys/i386/conf files.i386 src/sys/kern kern_fork.c  src/sys/libkern arc4random.c src/sys/sys libkern.h
Message-ID:  <v04205503b469524d12f0@[195.238.21.204]>
In-Reply-To: <19991129153639.B2999@spirit.jaded.net>
References:  <Pine.BSF.4.21.9911291103500.51314-100000@hub.freebsd.org> <v0420551bb4688f87fb80@[195.238.21.204]> <19991129153639.B2999@spirit.jaded.net>

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At 3:36 PM -0500 1999/11/29, Dan Moschuk wrote:

> One of the benefits of using an algorithm designed by a professional
> cryptographer is that the algorithm is bound to be studied extensively, it
> doesn't neccessarily have to be from our code base.

	That's probably true of the crypto algorithms in question, but as 
Schneier has repeatedly pointed out, they are only a relatively small 
part of the overall picture.

	It is entirely possible (one might even argue highly likely) that 
a less well-tested routine (written by programmers of unknown skill 
levels) based on a set of algorithms chosen by a respected 
cryptographer might be much, *much*, *MUCH* less secure (when viewed 
as a whole), than a better tested routine that has withstood attacks 
over a longer period of time.


	If you can restrict yourself to just the crypto part, then you 
can argue that removing older (and presumably since proven to be less 
secure) crypto in favour of newer (at least believed to be more 
secure) algorithms is a good thing.

	One example of this might be choosing SHA-1 over MD5, since there 
are certain known weaknesses in some utilizations of MD5, which might 
point to broader (but not yet discovered) weaknesses, wherease no one 
has yet been able to find any inherent weaknesses in SHA-1.

	However, we very rarely have the luxury of being able to replace 
*just* the crypto part of one routine with the crypto part of 
another.  Instead, we need to view the whole as a collection of parts 
that need to be evaluated together, in which the crypto plays a 
critical but still relatively small part.

-- 
   These are my opinions -- not to be taken as official Skynet policy
  ____________________________________________________________________
|o| Brad Knowles, <blk@skynet.be>            Belgacom Skynet NV/SA |o|
|o| Systems Architect, News & FTP Admin      Rue Col. Bourg, 124   |o|
|o| Phone/Fax: +32-2-706.11.11/12.49         B-1140 Brussels       |o|
|o| http://www.skynet.be                     Belgium               |o|
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  Unix is like a wigwam -- no Gates, no Windows, and an Apache inside.
   Unix is very user-friendly.  It's just picky who its friends are.


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