[From nobody Tue Nov 18 17:28:04 2008 Return-Path: <p2p-hackers-bounces@lists.zooko.com> Received: from vscan-c.ucl.ac.uk by ess3.cs.ucl.ac.uk with UK SMTP id <g.09453-0@ess3.cs.ucl.ac.uk>; Sun, 27 Jan 2008 16:19:55 +0000 Received: from misfit.maski.org ([209.40.195.45]) by vscan-c.ucl.ac.uk with esmtp (Exim 4.60) (envelope-from <p2p-hackers-bounces@lists.zooko.com>) id 1JJAET-0005uo-Ql; Sun, 27 Jan 2008 16:19:46 +0000 Received: from misfit.maski.org (misfit.maski.org [127.0.0.1]) by misfit.maski.org (Postfix) with ESMTP id CAF76619B9D; Sun, 27 Jan 2008 16:19:21 +0000 (UTC) X-Original-To: p2p-hackers@lists.zooko.com Delivered-To: p2p-hackers@lists.zooko.com Received: from nooxie.zooko.com (unknown [207.7.131.41]) by misfit.maski.org (Postfix) with ESMTP id 308DA618A68 for <p2p-hackers@lists.zooko.com>; Sun, 27 Jan 2008 16:18:56 +0000 (UTC) Received: from [192.168.1.103] (unknown [209.97.232.250]) by nooxie.zooko.com (Postfix) with ESMTP id 81ACD14C9B7; Sun, 27 Jan 2008 09:23:26 -0800 (PST) Mime-Version: 1.0 (Apple Message framework v753) In-Reply-To: <001801c8609f$4e287540$ea795fc0$@net> References: <000501c8609a$6650a390$32f1eab0$@net> <001801c8609f$4e287540$ea795fc0$@net> Message-Id: <715BA506-132B-49F7-8008-306DB15B934A@zooko.com> From: zooko <zooko@zooko.com> Date: Sun, 27 Jan 2008 09:18:50 -0700 To: tahoe-dev@allmydata.org, theory and practice of decentralized computer networks <p2p-hackers@lists.zooko.com>, Cryptography <cryptography@metzdowd.com> X-Mailer: Apple Mail (2.753) Subject: Re: [p2p-hackers] [tahoe-dev] Surely M$ can patent this process? X-BeenThere: p2p-hackers@lists.zooko.com X-Mailman-Version: 2.1.9 Precedence: list Reply-To: theory and practice of decentralized computer networks <p2p-hackers@lists.zooko.com> List-Id: theory and practice of decentralized computer networks <p2p-hackers.lists.zooko.com> List-Unsubscribe: <http://lists.zooko.com/mailman/listinfo/p2p-hackers>, <mailto:p2p-hackers-request@lists.zooko.com?subject=unsubscribe> List-Archive: <http://lists.zooko.com/pipermail/p2p-hackers> List-Post: <mailto:p2p-hackers@lists.zooko.com> List-Help: <mailto:p2p-hackers-request@lists.zooko.com?subject=help> List-Subscribe: <http://lists.zooko.com/mailman/listinfo/p2p-hackers>, <mailto:p2p-hackers-request@lists.zooko.com?subject=subscribe> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Sender: p2p-hackers-bounces@lists.zooko.com Errors-To: p2p-hackers-bounces@lists.zooko.com X-UCL-MailScanner-Information: Please contact the UCL Helpdesk, helpdesk@ucl.ac.uk for more information X-UCL-MailScanner: Found to be clean X-UCL-MailScanner-From: p2p-hackers-bounces@lists.zooko.com X-Spam-Status: No [adding Cc: p2p-hackers and cryptography mailing lists as explained = below; Please trim your follow-ups as appropriate.] Dear Gary Sumner: On Jan 26, 2008, at 9:44 PM, Gary Sumner wrote: > I was researching on the weekend and came across Tahoe=85very = > exciting and can=92t wait to delve in and understand more in detail. > > I was reading over Plank=92s work around erasure encoding and that = > lead me to Tahoe. One thing that I was really looking for was to be = > able to encrypt the data before storing it and so was very excited = > when I read your architecture doc and it says =93When a file is to be = > added to the grid, it is first encrypted using a key that is = > derived from the hash of the file itself.=94 This seems perfectly = > logical and natural way to apply this technique. However, = > researching also lead me to a patent M$ has been granted on this = > exact process: > > Encryption Systems and Methods for Identifying and Coalescing = > Identical Objects Encrypted with Different Keys - http:// = > patft.uspto.gov/netacgi/nph-Parser?Sect1=3DPTO2&Sect2=3DHITOFF&p=3D1&u=3D= % = > 2Fnetahtml%2FPTO%2Fsearch- = > bool.html&r=3D1&f=3DG&l=3D50&co1=3DAND&d=3DPTXT&s1=3D6983365.PN.&OS=3DPN/ = > 6983365&RS=3DPN/6983365 > I haven't read that patent, so I can't say whether it applies to what = allmydata.org Tahoe does or not. By default, for immutable files = (but not for mutable files or directories), Tahoe sets the encryption = key equal to the tagged hash of the file contents. (A tagged hash is = simply a hash of the data prefixed by a tag to distinguish it from = other uses of hash functions). You don't have to use Tahoe this way, = however: > The encryption before storing is critical for my application. > If, for any reason, you don't want to let your encryption key be = produced from the secure hash of the file contents, then Tahoe can = instead use a randomly-generated encryption key. The drawback of = doing it this way -- with a random encryption key -- is that you lose = the "deduplication" feature: two people who independently store the = same file contents will use twice as much space, instead of each of = them having a pointer to a single stored copy. The advantages of = doing it with a random encryption key are that you get a stronger = guarantee about the confidentiality of the contents of your files, = and it is faster as you don't need to process the whole file (in = order to generate the encryption key) before beginning to upload the = file. > Surely there must be prior art on this technique to refute this = > patent? > That's an interesting question, and I'm carbon-copying the p2p- = hackers and cryptography mailing lists to ask if anyone knows. I = learned about this technique from Jim McCoy and Doug Barnes in their = design of Mojo Nation. I don't remember whether this technique was = mentioned in Jim McCoy's personal communication of Mojo Nation to me = in the summer of 1998, but it was definitely present in the design = when I started working for Jim and Doug on Mojo Nation in 1999, and = when Mojo Nation was first announced to the world at DefCon in July = 2000 [1, 2]. I don't know if Jim came up with the idea ex nihilo or = was exposed to it in the swirling soup of ideas that we lived in at = the time: cypherpunks / Electric Communities (which had many ideas = gleaned from Xanadu) / Financial Cryptography / etc.. I remember reading about the newly announced Freenet project in 2000 = and being surprised at how many similarities its design had to our = unannounced Mojo Nation project. The influential Freenet paper [3] = was published in July, 2000 -- one month too late to count as prior = art for that patent, which was filed May 2000. However, that paper = was based on Ian Clarke's master's thesis, which was published in = 1999. Let's see... A there it is: [4]. Hm, no it does not seem to = contain the notion that the 2000 Freenet paper would popularize as = "Content Hash Keys". I've also just now re-read The Eternity Service (Anderson, 1996) [5], = and it, like Clarke 1999, omits details of encryption. It's an interesting puzzle of intellectual history. The idea = certainly seems to have been "in the air", as both Mojo Nation and = Freenet were working on it before the May 2000 patent submission by = Doceur et al., but Mojo Nation and Freenet each published the idea = shortly after May 2000. According to my limited understanding of = patent law, this means that they don't count as prior art on that = patent. Regards, Zooko [1] http://www.mccullagh.org/image/950-12/jim-mccoy-mojonation.html [2] http://web.archive.org/web/20001118214000/http:// = www.mojonation.net/docs/technical_overview.shtml [3] http://citeseer.ist.psu.edu/420356.html [4] http://citeseer.ist.psu.edu/380453.html [5] http://citeseer.ist.psu.edu/anderson96eternity.html _______________________________________________ p2p-hackers mailing list p2p-hackers@lists.zooko.com http://lists.zooko.com/mailman/listinfo/p2p-hackers ]