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RE: Updated c14n Spec

From: Petteri Stenius <Petteri.Stenius@remtec.fi>
Date: Fri, 16 Jun 2000 09:19:11 +0300
Message-ID: <CD0FF8F92CA8D311B9AB00105A14D5570B116A@server.remtec.fi>
To: "'David Blondeau'" <blondeau@intalio.com>, w3c-ietf-xmldsig@w3.org
Cc: XML DSig <w3c-ietf-xmldsig@w3.org>

You assume that the XML document constructor has properly declared all
namespaces that appear in XML attribute values. Of course there is nothing
an XML processor can do to verify this. A short sample:

<doc>
	<reference expr="foo:bar"/>
	<foo:bar xmlns:foo="uri"/>
</doc>

This is completely valid XML and the namespaces axis of the 'reference'
element is empty even if the attribute value refers to a namespace. One does
not have to declare the namespace at the 'doc' element level, and if this
document was constructed using DOM then the above XML representation would
most likely be the result.


Petteri


> -----Original Message-----
> From: David Blondeau [mailto:blondeau@intalio.com]
> Sent: Thursday, June 15, 2000 12:06 AM
> To: w3c-ietf-xmldsig@w3.org
> Cc: XML DSig
> Subject: Re: Updated c14n Spec
> 
> 
> > I need to read the attributes of a element anyway, and I 
> also need to sort
> > them using the attribute name and the namespace uri as sort 
> keys. This is
> > the minimum requirement in all cases.
> I just wanted to show that your suggestion was worst than the 
> one in the
> draft because you have to be carefull about namespace prefixes used in
> attributes values. Your suggestion was to put  namespaces 
> only when they are
> used, my question is then: how do you know a prefix is used 
> in an attribute
> value?
> For that, you need to know all the prefixes in scope so you 
> need to walk on
> the tree to get the namespaces prefixes, and then do a really 
> difficult
> parsing job...
> No matter how you are doing it, you need all the namespace 
> declarations in
> scope for each element.
> 
> The january draft of C14n was easier on this point since it 
> didn't care
> about prefixes in attribute values.
> 
> David
> 
> 
Received on Friday, 16 June 2000 02:18:55 GMT

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