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RE: Whitespace

From: Brian LaMacchia <bal@microsoft.com>
Date: Fri, 11 Jan 2002 17:30:20 -0800
Message-ID: <BCDB2C3F59F5744EBE37C715D66E779C0290318C@red-msg-04.redmond.corp.microsoft.com>
To: <reagle@w3.org>
Cc: <w3c-ietf-xmldsig@w3.org>
I object to the proposal for including xml:space as an attribute of
SignatureProperties and Object for the following reasons:

1) This change introduces new interop requirements that we'd have to
test & meet in order to progress to Standard/Recommendation.
(Specifically, do applications properly interop if the attribute is
xml:space=default or xml:space=preserve.) 

2) I'm not convinced that supporting or depending on xml:space is the
right way to go.  If we need space-removal semantics I believe we should
do that with a better, XML Schema-aware canonicalization algorithm.

2a) Related to (2), in the existing two C14N algorithms the presence or
absence of an xml:space attribute doesn't actually affect the execution
of the algorithm (indeed: per the C14N spec, "All whitespace in
character content is retained") so I can't see this change being
justified on grounds of affecting the actual signature; the xml:space
would instead only be of significance to an app-level semantic that
interprets the contents of an Object element.

3) If we were going to put the attribute anywhere, then I believe
Joseph's comment is correct that it would be more appropriate for the
attribute to go on ext:Foo.  (Notice that since dsig:Object does not
itself have any significant semantic beyond a mere container, it is the
case that in fact doing it this way (on ext:foo) is fully equivalently

4) Finally, as the owner of a V1-compliant implementation that has been
frozen for months, I must object to any change that could potentially
make my implementation non-compliant.

So, basically, it's too little and too late.  The chance that
implementations might become non-compliant at this point, combined with
the time it would take to perform new interop testing, is sufficient
reason in my opinion to reject this proposal.  


-----Original Message-----
From: Joseph Reagle [mailto:reagle@w3.org] 
Sent: Tuesday, January 08, 2002 1:08 PM
To: Rich Salz; w3c-ietf-xmldsig@w3.org
Subject: Re: Whitespace

On Tuesday 08 January 2002 13:04, Rich Salz wrote:
> I believe that the SignatureProperty and Object element definitions
> should be modified to allow the xml:space attribute.  I'm proposing
> those two, because I believe those are the most likely elements within
> ds:Signature that will be covered by a signature.

Hi Rich, we are on the very cusp (I hope this week) of getting IESG 
approval and moving forward. Consequently, the only tweaks we've
since we entered PR are those that don't upset *any* person, previous 
concensus, instances, or implementations: just small tweaks that  make
spec better in everyone's eyes.

To implement your proposal we'd have two options:
1. Add the following to the two element definitions that would then
xml:space and xml:lang
  <anyAttribute namespace="http://www.w3.org/XML/1998/namespace"/> 
2. Or to enable xml:space but preclude xml:lang:
  <xsd:import namespace="http://www.w3.org/XML/1998/namespace" 
     <xsd:attribute ref="xml:space" use="optional"/>

I don't see either violating my threshold of slipping it in if others
this is a good idea and no one objects. (The first is better IMHO.)

However, if you did this, wouldn't this also preserve the whitespace 
between the ds:Object and the ext:Foo? I'd think that if you're worried 
about the whitespace in ext:Foo, it should have the xml:space, not 
necessarily the ds:Object?


Joseph Reagle Jr.                 http://www.w3.org/People/Reagle/
W3C Policy Analyst                mailto:reagle@w3.org
IETF/W3C XML-Signature Co-Chair   http://www.w3.org/Signature/
W3C XML Encryption Chair          http://www.w3.org/Encryption/2001/
Received on Friday, 11 January 2002 20:30:56 UTC

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