Exclusive XML Canonicalization, Version 1.0
RFC 3741
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Type |
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RFC - Informational
(March 2004; Errata)
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Last updated |
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2015-10-14
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IETF
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plain text
pdf
html
bibtex
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WG state
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(None)
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Document shepherd |
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No shepherd assigned
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| IESG |
IESG state |
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RFC 3741 (Informational)
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Consensus Boilerplate |
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Unknown
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Telechat date |
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Responsible AD |
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Russ Housley
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IESG note |
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The revised draft includes the changes requested by Randy Bush. It is back on the agenda to confirm that there are no further concerns.
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Send notices to |
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(None)
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Network Working Group J. Boyer
Request for Comments: 3741 PureEdge Solutions
Category: Informational D. Eastlake 3rd
Motorola
J. Reagle
W3C
March 2004
Exclusive XML Canonicalization, Version 1.0
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
Canonical XML specifies a standard serialization of XML that, when
applied to a subdocument, includes the subdocument's ancestor context
including all of the namespace declarations and attributes in the
"xml:" namespace. However, some applications require a method which,
to the extent practical, excludes ancestor context from a
canonicalized subdocument. For example, one might require a digital
signature over an XML payload (subdocument) in an XML message that
will not break when that subdocument is removed from its original
message and/or inserted into a different context. This requirement
is satisfied by Exclusive XML Canonicalization.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology. . . . . . . . . . . . . . . . . . . . . . . 2
1.2. Applications . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Limitations. . . . . . . . . . . . . . . . . . . . . . . 5
2. The Need for Exclusive XML Canonicalization. . . . . . . . . . 5
2.1. A Simple Example . . . . . . . . . . . . . . . . . . . . 6
2.2. General Problems with re-Enveloping. . . . . . . . . . . 7
3. Specification of Exclusive XML Canonicalization. . . . . . . . 8
3.1. Constrained Implementation (non-normative) . . . . . . . 9
4. Use in XML Security. . . . . . . . . . . . . . . . . . . . . . 10
5. Security Considerations. . . . . . . . . . . . . . . . . . . . 12
5.1. Target Context . . . . . . . . . . . . . . . . . . . . . 12
Boyer, et al. Informational [Page 1]
RFC 3741 Exclusive XML Canonicalization March 2004
5.2. 'Esoteric' Node-sets . . . . . . . . . . . . . . . . . . 13
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1. Normative References . . . . . . . . . . . . . . . . . . 13
6.2. Informative References . . . . . . . . . . . . . . . . . 14
7. Acknowledgements (Informative) . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
The XML Recommendation [XML] specifies the syntax of a class of
objects called XML documents. The Namespaces in XML Recommendation
[XML-NS] specifies additional syntax and semantics for XML documents.
It is normal for XML documents and subdocuments which are equivalent
for the purposes of many applications to differ in their physical
representation. For example, they may differ in their entity
structure, attribute ordering, and character encoding. The goal of
this specification is to establish a method for serializing the XPath
node-set representation of an XML document or subset such that:
1. The node-set is minimally affected by any XML context which has
been omitted.
2. The canonicalization of a node-set representing well-balanced
XML [XML-Fragment] will be unaltered by further applications of
exclusive canonicalization.
3. It can be determined whether two node-sets are identical except
for transformations considered insignificant by this
specification under [XML, XML-NS].
An understanding of the Canonical XML Recommendation [XML-C14N] is
required.
The World Wide Web Consortium Recommendation corresponding to this
RFC is at: http://www.w3.org/TR/xml-exc-c14n. Errata are located at
http://www.w3.org/2002/07/xml-exc-c14n-errata.
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [Keywords].
The XPath 1.0 Recommendation [XPath] defines the term node-set and
specifies a data model for representing an input XML document as a
set of nodes of various types (element, attribute, namespace, text,
comment, processing instruction, and root). The nodes are included
in or excluded from a node-set based on the evaluation of an
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