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Re: XML Schema base64Binary simple type

From: Joseph M. Reagle Jr. <reagle@w3.org>
Date: Tue, 12 Jun 2001 16:27:39 -0400
Message-Id: <>
To: "Gregor Karlinger" <gregor.karlinger@iaik.at>
Cc: "XMLSigWG" <w3c-ietf-xmldsig@w3.org>, w3c-xml-schema-wg@w3.org
Right. This issue is under discussion by the Schema WG (both the white space 
preservation/omission issue in general and the 'collapse' facet in 
particular). Depending on the outcome, we may have to revert to our own 
definition of base64.

At 06:18 6/9/2001, Gregor Karlinger wrote:
>I think the current Schema definition at least of the
>DigestValueType leads to severe problems:
>DigestValueType is derived by restriction from the XML Schema
>simple type base64Binary. The *FIXED* value of the "whitespace"
>facet is "collapse" for all atomic types other than string [1].
>A value of "collapse" means that a validating parser normalizes
>whitespaces in the string content of the DigestValue element.
>This behaviour could break the signature, if the signer produces
>a digest value containing sequences of whitespaces, and the verifier
>schema validates the signature.
>Since the "collapse" value for the "whitespace" faced is *FIXED* we
>cannot derive our DigestValueType from "base64Binary". Instead we
>could derive the type by restriction from "string" since then we
>are allowed to change the value of the "whitespace" facet to
>"preserve" [1].
>This issue is vital with respect to DigestValueType, but maybe it also
>makes sence to change the definition of SignatureValueType, CryptoBinary,
>X509SKI, ... since this elements are also likely to be covered by a
>signature, and then the same problem applies there.
>[1] http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/#rf-whiteSpace
>Liebe Gruesse/Regards,
>DI Gregor Karlinger
>Phone +43 316 873 5541
>Institute for Applied Information Processing and Communications

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 Tuesday, 12 June 2001 16:27:58 UTC

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