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Namespace treatment for C14N

From: Hiroshi Maruyama <MARUYAMA@jp.ibm.com>
Date: Mon, 7 Jun 1999 09:19:17 +0900
To: w3c-ietf-xmldsig@w3.org, reagle@w3.org
Message-ID: <49256789.00022CE2.00@d22mta10.yamato.ibm.com>



Joseph,
I have been following the discussion on C14N of the Syntax group.  One of
the things that are not resolved is how to handle namespace prefixes.
Here is an idea that Donald and I came up with.

1. Namespace prefixes are always expanded to its original URI (including
the default namespace)
2. Hex coding of MD5 of the Expanded URI is used as the new prefix.

Here is an example

Document A
===========
<?xml version="1.0" encoding="Shift_JIS"?>
<root>
 <hello xmlns:myns="http://monet.trl.ibm.com/myschema"
        xmlns="http://default.sch">
   <myns:goodbye/>
 </hello>
</root>

The canonical form of this document may look like this.
Document B = C14N(A)
====================
<?xml version="1.0" encoding="UTF-8"?>
<root>
 <_596C7D3063274C61632270212A4E5667:hello
xmlns:_5628413F365675591241005E3B123D63="http://monet.trl.ibm.com/myschema"
xmlns:_596C7D3063274C61632270212A4E5667="http://default.sch">

<_5628413F365675591241005E3B123D63:goodbye></_5628413F365675591241005E3B123
D63:goodbye>
 </_596C7D3063274C61632270212A4E5667:hello>
</root>

Here, the MD5 values of "http://monet.trl.ibm.com" and "http://default.sch"
are 5628413F365675591241005E3B123D63 and 596C7D3063274C61632270212A4E5667,
respectively.  We need the underscore character to make it a legal XML
name.


This is not particularly readable but satisfies the following two
requirements.
  1. B is wellformed  (well-formedness)
  2. C14N(B)=B        (fixed point property)


--
Hiroshi Maruyama
Manager, Network Applications, Tokyo Research Laboratory
+81-462-73-4576, maruyama@jp.ibm.com
Also Associate Professor, Dept. of Computer Science, Tokyo Institute of
Technology
+81-3-5734-3953, maruyama@cs.titech.ac.jp


From: "Joseph M. Reagle Jr." <reagle@w3.org> on 99/06/03 09:00 PM

To:   "IETF/W3C XML-DSig WG" <w3c-ietf-xmldsig@w3.org>
cc:    (bcc: Hiroshi Maruyama/Japan/IBM)
Subject:  XML Infoset (Minutes:1999.06.02 XML Syntax WG)





Note that the XML people have identified a significant amount of overlap
between C14N (Canonicalization) and the Infoset working group. If people
are
interested in the C14N issues, I suggest they look at the most recent
Infoset Draft. [1] I hope the Syntax WG will have a first public WD prior
to
the IETF meeting -- but I'm not convinced we will.


[1] http://www.w3.org/TR/xml-infoset

Forwarded Text ----
 Date: Wed, 02 Jun 1999 22:12:29 -0700
 To: "XML Syntax WG" <w3c-xml-syntax-wg@w3.org>
 From: Tim Bray <tbray@textuality.com>
 Subject: Minutes:1999.06.02 XML Syntax WG

...
 4. Canonicalization

 NOTE: James Tauber *does* have time to put into this, but wants a
       co-editor
 ACTION: Chairs to recruit co-editor

 Issue: possible overlap with Infoset
 CONSENSUS: There is a real co-ordination issue here
 CONSENSUS: Portions of XML documents considered "Required" should be
            identical to that included in the canonical form.
 ACTION: T.Bray to send message to Megginson, cc the CG, noting this.
 CONSENSUS: In section 3, use infoset terminology & be consistent
 ACTION: T.Bray, to XML-i-fy the spec
 CONSENSUS: Express the material in section 4 in algorithms

End Forwarded Text ----
_________________________________________________________
Joseph Reagle Jr.
Policy Analyst      mailto:reagle@w3.org
XML-DSig Co-Chair   http://w3.org/People/Reagle/
Received on Sunday, 6 June 1999 20:19:48 GMT

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