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Re: Chartering work has started for a Linked Data Signature Working Group @W3C

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Wed, 12 May 2021 13:47:17 -0400
To: semantic-web@w3.org
Message-ID: <057fc436-213a-e837-a524-86971c35bb31@gmail.com>
I was looking through the draft charter.  Under the suggestion that RDF and 
Linked Data are synonyms we get the following deliverables.

RDF Dataset Canonicalization (RDC)
RDF Dataset Hash (RDH)
RDF Integrity (RI)
RDF Security Vocabulary (RSV)

I understand RDC, which is existing work, and RDH, which is also very close to 
existing work. I think I understand RI, which appears to be nothing more than 
the writing down of the necessary information to be able to verify signatures 
and similar things. Then RSV is just a vocabulary for these things.

So far, so good.

But when I look at the examples in the proposed source of RI, I get confused.  
I see there an example of adding a signature into what looks like a JSON-LD 
document.  As far as I can tell, this JSON-LD document, EXAMPLE 1, produces an 
empty graph but this depends on the contents of the context document at 
https://w3id.org/identity/v1. The signed document, EXAMPLE 2, also produces an 
empty graph but this depends on the contents of two documents, neither of 
which are the context document for the original document.  So I'm very puzzled 
as to just what is going on here.

OK, maybe all this is just about some aspect of JSON-LD, so I considered 
signing a Turtle document.  Here is a Turtle document:

@prefix foaf: <http://xmlns.com/foaf/0.1/> .

<alice> foaf:name "Alice" .


I quickly run into two problems.

First, where is the signature supposed to go to make a signed document?  I 
suppose that it can be just fit into comments.

Second, what is the RDF graph resulting from this document?  That depends on 
the base IRI, which can be influenced by the location of the document.  So 
will there have to be an extra location provided as input to RDC and 
associated with the signature?  This issue also appears in JSON-LD documents.

I couldn't find any discussion of these issues in the input documents for the 
proposed WG.  I expected to see something saying how to add signatures to RDF 
concrete syntaxes and something that excluded documents with relative IRIs or 
somehow handled relative IRIs.  I also expected to see something that worked 
for JSON-LD documents.

So I'm rather confused as to just how the WG is going to do what it needs to do.


peter
Received on Wednesday, 12 May 2021 17:48:32 UTC

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