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Re: CC/PP, RDF and trust issues

From: Sergey Melnik <melnik@db.stanford.edu>
Date: Thu, 27 Apr 2000 13:36:21 -0700
Message-ID: <3908A4C5.6C204FC0@db.stanford.edu>
To: Graham Klyne <GK@dial.pipex.com>
CC: www-rdf-interest@w3.org, CC/PP WG list <w3c-ccpp-wg@w3.org>
Graham,

there have been some discussion relevant to building a Web of Trust on
this list, in particularly with respect to signing RDF *content*. It
seems important to me that the algorithms for signing RDF operate on the
RDF model rather than using a particular serialization syntax like the
current XML-based one. Especially, if the syntax evolves over time.

You can find a summary of some ideas of how that can be done at

	http://nestroy.wi-inf.uni-essen.de/rdf/sum_rdf_api/

The above description of the algorithm is based on the working code
downloadable from

	http://www-db.stanford.edu/~melnik/rdf/api.html

In this approach, a cryptographic digest of a statement or a whole model
is taken to be the ID of the corresponding statement or model. Thus,
reification comes "for free", i.e. one can make assertions about models
directly by using their digest-based IDs.

I believe that RDF is a great way of establishing trust on the Web and
you are on the right path. I'm looking forward to hearing more about
your efforts!

Sergey


Graham Klyne wrote:
>
> [...]
>
> In private discussions, a model has emerged in which an "assurance"
> property can be applied to a reification of the RDF statements, whose
> object is [an identifier of] the principal who signed the original expression.
>
> [...]
>
> It seems that the shift from "signature" to "assurance" parallels the
> distinction between the serialization of an RDF graph, and the abstract
> graph itself.  A signature, by its nature, applies to the serialized form,
> not the graph, but it does confer information that is meaningful as part of
> the knowledge potentially represented by the graph.
>
> [...]
>
> Implicit in this question is the idea that dealing directly with
> reification in the CC/PP model will create a significant barrier to its
> adoption.  The CC/PP requirements document has already attracted some
> public comment that it is over-complex;  irrespective of whether such
> comments are justified, they send a signal that employing the full
> expressive power of RDF will likely be problematic.
>
> [...]
>
> (c) if such an approach is to be adopted, or indeed any other approach, it
> may be that this is something that is going to be a common requirement for
> all sorts of RDF applications.  Therefore, it seems appropriate that it is
> defined as a common RDF facility rather than something that is specific to
> CC/PP.  Has any substantial work in this area already tackled by the RDF
> community?
>
> [...]
>
> Given that CC/PP is committed to be built upon RDF, it seems desirable to
> engage as much RDF expertise as we can in the CC/PP design.  It is
> important for us to find a design for CC/PP that is direct and intuitive
> for developers and users, and that also does not violate the RDF model or
> common usage.  One area where this seems to be particularly important is
> that the trust issues are resolved cleanly and carefully.
Received on Thursday, 27 April 2000 16:26:02 GMT

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