Copyright © 1999 W3C (MIT, INRIA, Keio), All Rights Reserved. W3C liability, trademark, document use and software licensing rules apply.
This is a W3C Note produced as a deliverable of the XML Syntax WG according to its charter. A list of current W3C Working Drafts and Notes can be found at http://www.w3.org/TR.
This document is a work in progress representing the current consensus of the W3C XML Syntax Working Group. This version of the XML Canonicalization Requirements document has been approved by the XML Syntax Working Group and the XML Plenary to be posted for review by W3C members and other interested parties. Publication of this specification does not imply endorsement by the W3C membership. Comments should be sent to the automatically and publicly archived email list: firstname.lastname@example.org.
This document is being processed according to the following review schedule:
|XML Syntax WG sign off||1999/05/26||Done||XML Syntax WG|
|XML CG Review||199/05/28||Done||XML Syntax WG|
|XML-DSig review||1999/06/4||Done||XML Syntax WG, W3C/IETF XML-DSig WG, email@example.com|
|XML Plenary sign off||1999/06/4||Donefirstname.lastname@example.org, email@example.com, firstname.lastname@example.org|
|Publish as W3C Note||1999/06/7||Doneemail@example.com|
|Checkpoint of comments||1999/06/28||Underwayfirstname.lastname@example.org|
Comments about this document should be submitted to the "contact" listed above for each process.
This document lists the design principles, scope and requirements for the Canonicalization of XML for digital signatures in XML and XML Processor conformance. These are being developed by the World Wide Web Consortium's XML Syntax Working Group.
The XML 1.0 Recommendation [XML] describes the syntax of a class of data objects called XML documents. It is possible, however, for logically equivalent XML documents to differ in their physical representation. In particular, two equivalent XML documents may differ on such issues as physical (i.e. entity) structure, attribute ordering, character encoding and insignificant whitespace. This means that equivalence testing cannot be done at the byte level for arbitrary XML documents. Though, byte level equivalence testing is useful in the domain of digital signatures for XML.
Work has started elsewhere on the broader question of digital signatures in XML [IOTP-DSig, Brown-XML-DSig, DOMHASH]. The W3C hosted a workshop on signed XML [DS-XML], and is forming a W3C/IETF XML-DSig WG [XML-DSig].
The Canonical XML specification aims to introduce a notion of equivalence between XML documents which can be tested at the syntactic level and, in particular, by byte-for-byte comparison. It shall describe the canonicalization of XML documents such that logically equivalent documents will have the same byte-for-byte representation. This form is referred to as the canonical form of the document.