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RE: exc c14n bugs

From: John Boyer <JBoyer@PureEdge.com>
Date: Tue, 11 Jun 2002 14:47:44 -0700
Message-ID: <7874BFCCD289A645B5CE3935769F0B52328818@tigger.PureEdge.com>
To: <reagle@w3.org>, "merlin" <merlin@baltimore.ie>
Cc: <w3c-ietf-xmldsig@w3.org>

Hi Joseph and Merlin,

The only problem with the proposed limitation is that, zen of the empty default namespace, explicitly declaring it at the apex node doesn't work because it is not represented by a node.  

Merlin, on this point I'd prefer it if you continued to 'argue' the point if there is indeed more to consider.  Right now, I think the xmlns="" warrants special-case handling because of the weird way it is represented, but I am prepared to be convinced otherwise (or even to continue with a minority opinion that doesn't become part of the spec). I have no vested interest in either approach, just a desire to have all points considered before a decision is made so that we can avoid making a bad choice if possible (or at least to make the least bad choice given what is currently known).  Regardless of the outcome, your thought-provoking insights are always welcome :-)

Thanks,
John Boyer

-----Original Message-----
From: Joseph Reagle [mailto:reagle@w3.org]
Sent: Thursday, June 06, 2002 10:19 AM
To: merlin; John Boyer
Cc: w3c-ietf-xmldsig@w3.org
Subject: Re: exc c14n bugs


On Thursday 06 June 2002 08:41 am, merlin wrote:
> I agree that omitting this definition does cause problems with
> (non-pejoratively) na´ve textual wrapping. In particular; pure
> c14n (as recommended by the spec) is not a good serializer
> for XML encryption because the wrapping and parsing language
> will cause problems.

As an aside, this xmlns="" problem when inserting an XML fragment into 
another instance is similar to the problems we discovered with xml:lang, 
xml:base, and xml:space [1]. Applications need to take care of of these 
sorts of attributes at the boundary of any subsetting and insertions... 
I've already added Merlin's proposed text to xenc for consideration, shoud 
we also add a line to [1]?

http://www.w3.org/Signature/Drafts/xml-exc-c14n.html#sec-Limitations
The XML being canonicalized may depend on the effect of xml namespace 
attributes, such as xml:lang, xml:space, and xml:base appearing in ancestor 
nodes. To avoid problems due to the non-importation of such attributes into 
an enveloped document subset, either they must be explicitly given in the 
apex nodes of the XML document subset being canonicalized or they must 
always be declared with an equivalent value in every context in which the 
XML document subset will be interpreted.
nt subset will be interpreted.
Received on Tuesday, 11 June 2002 17:48:19 GMT

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