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RE: Who says so? Cryptographic certificates to authenticate declarations of fact. [SEC=UNCLASSIFIED]

From: Alistair Miles <alistair.miles@zoo.ox.ac.uk>
Date: Thu, 18 Sep 2008 16:43:58 +0100
To: "'Murray, Paul'" <Paul.Murray@environment.gov.au>, <public-swd-wg@w3.org>
Message-ID: <000601c919a5$5db01990$19104cb0$@miles@zoo.ox.ac.uk>

Hi Paul, 

This is out of scope for SWD but definitely in scope for
semantic-web@w3.org.

You might also be interested in http://www.w3.org/2004/03/trix/ and
http://www4.wiwiss.fu-berlin.de/bizer/pub/Carroll_etall-WWW2005.pdf

--
Alistair Miles
Senior Computing Officer
Image Bioinformatics Research Group
Department of Zoology
The Tinbergen Building
University of Oxford
South Parks Road
Oxford
OX1 3PS
United Kingdom
Web: http://purl.org/net/aliman
Email: alistair.miles@zoo.ox.ac.uk
Tel: +44 (0)1865 281993


> -----Original Message-----
> From: public-swd-wg-request@w3.org [mailto:public-swd-wg-
> request@w3.org] On Behalf Of Murray, Paul
> Sent: 28 August 2008 03:53
> To: public-swd-wg@w3.org
> Subject: Who says so? Cryptographic certificates to authenticate
> declarations of fact. [SEC=UNCLASSIFIED]
> 
> Hi all - I'm new to this list (new to RDF), so sorry if this has been
> done to death already.
> 
> AFAIK, the semantic web consists of all RDF documents everywhere.
> Looking through RDF: you can say something about two things [sky has-
> property is-blue], but there doesn't seem to be an obvious way to
> decorate the act of declaring such a thing, aside from making a note of
> the url you fetched it from.
> 
> Firstly, such decorations are of semantic interest. You want to know
> things like: who says so? How sure are they? Does this fact only apply
> during a certain time, or in certain circumstances? Is it meant to be a
> promulgation of a standard? A statement of commonly accepted fact? A
> hope or a wish that something ought to be true? A hypthesis?
> 
> Secondly ... just let me toss in the word "porn spammer". If every
> declaration of fact is the same as any other, and if facts begin to
> move across the semantc web (caches and so on), and if it starts to
> become important, then you are going to get commercial spam.
> 
> The other problem is liars. What happens when a liar publishes an RDF
> document that [X has-propery is-gay], or whatever?
> 
> Now at present, it would seem that you *could* do this stuff in RDF,
> with a little fooling about. You need a well-known verb that says "X
> is-a-caveated-version-of Y", where Y is some other operator.
> 
> sky has-property-005 is-blue
> sky is-above-005 the-ground
> has-property-005 is-a-caveated-version-of has-property
> is-above-005 is-a-caveated-version-of is-above
> has-property-005 asserted-at 1-Jul-07
> has-property-005 asserted-by encyclopedia-britannica
> is-above-005 asserted-at 1-Jul-07
> is-above-005 asserted-by encyclopedia-britannica
> 
> 
> Perhaps we could make this a little less bulky with inheritance
> operators:
> "A inherits-subject  B:  B D E -> A D E"
> and maybe another one Y that allows you to reverse the arguments
> "A inherits-object B:  B D E -> A D E"
> Heck, why not complete it
> "A inherits-verb B:  D B E -> D A E"
> 
> I'm not sure whether "is-a-caveated-version-of" is the same as
> "inherits-verb". It is if you decide to drop all the caveats. In any
> case:
> 
> sky has-property-005 is-blue
> sky is-above-005 the-ground
> has-property-005 is-a-caveated-version-of has-property
> is-above-005 is-a-caveated-version-of is-above
> has-property-005 inherits-subject  download-005
> is-above-005 inherits-subject  download-005
> download-005 asserted-at 1-Jul-07
> download-005 asserted-by encyclopedia-britannica
> 
> ====================================
> 
> The thing is, whenever you read a fact from some other source, there is
> an implicit performative. My declaration "the sky is blue", when you
> read it, nessesarily becomes "Paul Murray said in an email to the
> working group at this date that the sky is blue". This wrapping happens
> whenver a fact is transferred from one place to another.
> 
> However, in a semantic web where facts are moved from place to place,
> archived, clustered and so on, the necessity of tracking "who says so,
> how and when?" Means that our facts get wrapped in the details of the
> transfers "database a says that archive b says that encyclopedia
> britannica says that the sky is blue". Every time we import a fact from
> anywhere, we have to create another verb.
> 
> There is a way of avoiding this: a trusted cryptographic signature
> allows us to collapse these layers of packaging. Thus, when
> encyclopedia britannica asserts a fact, it can be asserted with an
> attached signature. If I get that fact from an archive or other man-in-
> the-middle, and the signature checks out (that is: I trust the CA), I
> do not need to keep the fact that I got it from an archive. As far as I
> am concerned, it comes straight from britannica.
> 
> The details are somewhat tricky. Should each fact be individually
> signed? Is there a way of bundling them, somehow? Of course, if you
> bundle them then in order to check that the signature applies you need
> the entire bundle. You could simply permit the entire RDF docment to be
> signed out-of-band (eg: http authentication, an xml envelope), but that
> means that someone getting your facts that you got from Britannica only
> has your word for it. Unless they trust you to make declarations of the
> form "I got this from britannica".
> 
> But the sematic web is going to need something like this, and it's also
> going to need a well-known set of very basic verbs about other verbs: A
> implies B, A means the same a B, A is the negation of B, and so on.
> 
> May I also take the opportunity to complain about the lack of an XSD?
> Describing RDF in RDF is fine, but RDF is transferred in XML documents,
> read in with an XML parser, and I'd like to be able to validate it at
> that level.
> 
> 
> 
> 
> 
> 
> 
> 
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Received on Thursday, 18 September 2008 15:44:36 UTC

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