From owner-freebsd-security Thu Aug 29 12:27:18 2002 Delivered-To: freebsd-security@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6479537B400 for ; Thu, 29 Aug 2002 12:27:14 -0700 (PDT) Received: from snark.piermont.com (snark.piermont.com [166.84.151.72]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4FA4443E72 for ; Thu, 29 Aug 2002 12:27:13 -0700 (PDT) (envelope-from perry@piermont.com) Received: by snark.piermont.com (Postfix, from userid 1000) id 3EA52D97C9; Thu, 29 Aug 2002 15:27:07 -0400 (EDT) To: "Dave Feustel" Cc: "Karsten W. Rohrbach" , , "Matthias Buelow" , "Stefan =?iso-8859-1?q?Kr=FCger?=" , , , Subject: Re: 1024 bit key considered insecure (sshd) References: <20020828200748.90964.qmail@mail.com> <3D6D3953.6090005@mukappabeta.de> <20020828224330.GE249@localhost> <87k7mamc2s.fsf@snark.piermont.com> <20020829091232.A53344@mail.webmonster.de> <87bs7ln66u.fsf@snark.piermont.com> <20020829155118.B63360@mail.webmonster.de> <871y8hn43d.fsf@snark.piermont.com> <20020829183858.A68055@mail.webmonster.de> <001301c24f7c$81b866c0$5892ee41@dafco6w9sb81bw> From: "Perry E. Metzger" Date: 29 Aug 2002 15:27:07 -0400 In-Reply-To: <001301c24f7c$81b866c0$5892ee41@dafco6w9sb81bw> Message-ID: <87elchzcs4.fsf@snark.piermont.com> Lines: 36 User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org "Dave Feustel" writes: > See _Cracking DES_ Wow. I'd never heard of that book before. I wonder why no one mentioned brute force attacks on DES to me. It might have been interesting to mention to my students in my annual graduate course in cryptography. > (http://www.amazon.com/exec/obidos/tg/detail/-/1565925203/qid=1030639763/sr=1-1/ref=sr_1_1/102-5391104-6813765?v=glance&s=books > > for a (by now obsolete) low-cost home-brew system > for cracking DES. The available FPGA hardware has advanced > considerably since this book was written. Don't try teaching grandpa to suck eggs. For extra credit, present the difference in computational complexity between cracking a 56 bit DES key and factoring a 1024 bit integer. And no, the difference is not a factor of 2^968. You should especially go to the back of the room if you thought it was a straight factor of 968, and if you thought it was a factor of 18 because 1024 is about 18 times larger than 56 you should confine your future job searches to the food service and waste disposal industries. For extra extra credit, figure out how many Virtex II FPGAs you would need to try out Dan's new number field sieve trick with a 1024 bit key if you want a result in one year. The Virtex II is ideal because of its size and the presence of several IBM PPC cores on board. Hint: it is not clear Xilinx can produce that many Virtex IIs for you at the moment, though I'm sure they could scale up production for it. -- Perry E. Metzger perry@piermont.com -- "Ask not what your country can force other people to do for you..." To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message