Copyright © 1999 The Internet Society & W3C (MIT, INRIA, Keio), All Rights Reserved. W3C liability, trademark, document use and software licensing rules apply.
This is a WG XML Signature Requirements consensus candidate draft. Upon final confirmation by the WG, this document will be published as a working-draft/ietf-draft. This forthcoming publication will be similar to a last-call in that it is asking for substantive community wide review, particularly with respect to the dependencies identified in this document. It is different from a last call in that it is not intended to be advanced to a W3C Proposed Recommendation. Once dependencies and commitments have been confirmed with the identified WGs, this document may be advanced as an IETF Informational RFC. Aside from these caveats, this WG deliverable is largely on schedule with respect to the timeline in the WG Charter:
Aug 99 Requirements document to Last Call for NOTE / Informational RFC
This document attempts to capture the Working Group's consensus though it
contains points which are still in dispute or not well specified. Issues
which are still being actively discussed during the publication of this document
class="discuss" and rendered as color:navy by style sheet
compliant applications. Editorial comments about a discussion point are of
class="comment" and rendered in a box with a light background.
Please send comments to the editor <email@example.com> and cc: the list <firstname.lastname@example.org>. Publication as a Working Draft does not imply endorsement by the W3C membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite W3C Drafts as other than "work in progress".A list of current W3C working drafts can be found at http://www.w3.org/TR. Publication as a Working Draft does not imply endorsement by the W3C membership.
This document lists the design principles, scope and requirements for the XML Digital Signature specification.
The XML 1.0 Recommendation [XML] describes the syntax of a class of data objects called XML documents. The mission of this working group is to develop a XML syntax used for representing signatures on digital content and procedures for computing and verifying such signatures. Signatures will provide data integrity, authentication, and/or non-repudiatability.
This document lists the design principles, scope, and requirements over three things: (1) the scope of work available to the WG, (2) the XML signature specification, and (3) applications that implement the specification. It includes requirements as they relate to the signature syntax, data model, format, cryptographic processing, and external requirements and coordination. Those things that are required are designated as "must," those things that are optional are designated by "may," those things that are optional but recommended are designated as "should."
XML-signatures are generated from a hash over the canonical form of a signature manifest. The manifest includes references to Web resources, the hash of the resource content (or its canonicalized form), and (optionally) the resource content type. [Brown, List(Solo)] Web resources are defined as any digital content content that can be addressed using the syntax of XLink locator [XLink]).
Scenarios are being explored which examine the ability to sign without requiring
a manifest whereas the scope of the signed content is designated by the relative
placement of signature elements in the XML stream/tree. For instance:
<html> .....</body><dsig xmlns="http://..."
xmlns="http://..."> ... </dsig></html>
See the draft definitions document [Defn] for specific definitions of signature validation and trust validation.
The WG may specify security requirements that constrain the operation of these dependencies to ensure consistent and secure signature generation and operation. [Oslo]
The specification must permit the use of varied digital signature and message authentication codes, such as symmetric and asymmetric authentication schemes as well as dynamic negotiation of keying material. [Brown] Resource or algorithm identifier are a first class objects, and must be addressable by a URI. [Beners-Lee, Reagle]
An XML-signature must be a well-formed XML document. [Charter]
We are considering a restatement of this requirement to provide for XML-signatures being included within other doucuments: the signature is not a document itself.
An XML document of a certain type must still be recognizable as its original type when signed. For example, an XML form, when signed, should still be recognizable as a XML form to its application after it has been signed. [WS-summary]
In the event of redundant attributes within the XML Signature syntax and relevant cryptographic blobs, XML Signature applications prefer the XML Signature semantics. [awaiting clarification - Reagle.]
This issue is awaiting further clarification as we get closer to a syntax proposal the WG finds acceptable and we gain some sense of how applications will operate. For instance, instead of an application preferring one semantic to another, it might simply throw an error condition.
XML Package Working Group: signed content in/over packages.
XML Fragement Working Group: signing portions of XML content.
Members of the WG are very interested in signing and processing XML fragments and packaged components. Boyer asserts that [XML-fragment] does not "identify non-contiguous portions of a document in such a way that the relative positions of the connected components is preserved." Packaging is a capability critical to XML-Signature applications, but it is clearly dependent on clear trust/semantic definitions, package application requirements, and even cache-like application requirements. It is not clear how this work will be addressed.
The work of producing this specification was accomplished by the membership of the IETF/W3C XML Signature Working Group (WG). The list of contributors below was generated by the process specified in the XML Signature WG Contributor Policies.
Mark Bartel (JetForm Corporation ), John Boyer (UWI.com), Richard Brown (Globeset), Donald Eastlake (Co-Chair, IBM ), Barbara Fox (Microsoft ), Todd Glassey (Meridianus/GMTsw ), Phillip Hallam-Baker (VeriSign Inc ), Richard Himes (US District Court of New Mexico), Peter Lipp (IAIK TU Graz ), Hiroshi Maruyama (IBM ), Joseph Reagle (Co-Chair, W3C), Chris Smithies (PenOp), David Solo (Citigroup), Winchel "Todd" Vincent (GSU)