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Re: *Major* problem with xml:id in canonical XML

From: Chris Lilley <chris@w3.org>
Date: Mon, 24 Jan 2005 18:55:22 +0100
Message-ID: <212735882.20050124185522@w3.org>
To: Daniel Veillard <veillard@redhat.com>
Cc: Elliotte Harold <elharo@metalab.unc.edu>, public-xml-id@w3.org

On Monday, January 24, 2005, 6:48:32 PM, Daniel wrote:


DV> On Mon, Jan 24, 2005 at 11:51:37AM -0500, Elliotte Harold wrote:
>> I think the canonical XML spec clearly intended that all attributes in
>> the XML namespace have scope over their descendants, but that's not 
>> really true for xml:id.

DV> Arghh, this sounds like a bug in XML Canonicalization v 1.0, the
DV> assumption on any future extensions of the XML namespace sounds way
DV> out of scope to me. I would be surprized if they really expected
DV> that effect.

It sounds as if they extrapolated from three instances (xml:lang,
xml:space, xml:base) to state that all future xml:* attributes would be
inheritable.

>> This probably has downstream implications for XML digital signatures and
>> XML encryption, both of which depend on canonicalization.
>> 
>> Exclusive XML canonicalization does not inherit xml: attributes, and so
>> does not have this problem.
>> 
>> I am not sure what to suggest as a fix. It is still possible to 
>> canonicalize a document that uses xml:id. However, the results could be
>> quite unexpected and perhaps dangerous.

DV>   IMHO this should be raised as a bug in XML Canonicalization v 1.0

Certainly.

>> I wish I had a good answer here. I don't. I do think this should be 
>> discussed, and whatever resolution is reached needs to be called out in
>> the spec to warn people about this.

DV>   Looking at libxml2 implementation of c14n it seems affected by this,
DV> damn ...

DV> Daniel





-- 
 Chris Lilley                    mailto:chris@w3.org
 Chair, W3C SVG Working Group
 Member, W3C Technical Architecture Group

 As my dad would say - the first time something happens, its a mistake.
 The second time, its a coincidence. The third time, its traditional.
Received on Monday, 24 January 2005 17:55:23 UTC

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