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Re: FW: Base64

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 04 Sep 2001 12:08:22 +0100
To: reagle@w3.org
Cc: "Karl Scheibelhofer" <Karl.Scheibelhofer@iaik.at>, "Gregor Karlinger" <gregor.karlinger@iaik.at>, <merlin@baltimore.ie>, "XMLSigWG" <w3c-ietf-xmldsig@w3.org>, www-xml-schema-comments@w3.org
Message-ID: <f5b7kvfusbd.fsf@cogsci.ed.ac.uk>
Joseph Reagle <reagle@w3.org> writes:

> [cc:'d to schema comments since we need clarity on upcoming errata]
> 
> On Wednesday 29 August 2001 08:27, Karl Scheibelhofer wrote:
> > i just had the same problem in signing a base64 encoded certificate. i read
> > the according part of XML Schema and i think Xerxes behaves correctly here.
> 
> OK, first a summary of the issue if I can get it straight:
> 
> The xmldsig WG would like for schema validation to *not* collapse the 
> whitespace of base64 data in the *normalizedValue* of element content (as 
> specified in XML1.0). 

First check -- neither XML 1.0 nor XML Infoset specifies any notion of 
normalised value for element content.

Conformant XML Schema processors add a [schema normalized value]
property to element info items validated with simple type definitions.

> There are scenarios in which people validate the signature itself
> (instead of the data it signs which is served by an explicit
> transform) and this then affects the computation of the signature:
> the signature's base64 data [1] whitespace is collapsed:
> 
>    "For all *atomic* data-types other than string ... the value of 
>    whitespace is collapse." [2]

This describes the whitespace normalization that takes place in
computing the [schema normalized value] -- nothing to do with element
content per se.

ht
-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2001, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
Received on Tuesday, 4 September 2001 07:11:55 GMT

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