2.6.8 XML Digital Signatures (xmldsig)

NOTE: This charter is a snapshot of the 47th IETF Meeting in Adelaide, Australia. It may now be out-of-date. Last Modified: 03-Mar-00


J. Reagle <reagle@w3.org>
Donald Eastlake 3rd <dee3@torque.pothole.com>

Security Area Director(s):

Jeffrey Schiller <jis@mit.edu>
Marcus Leech <mleech@nortelnetworks.com>

Security Area Advisor:

Jeffrey Schiller <jis@mit.edu>

Mailing Lists:

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Description of Working Group:


Digital signatures provide integrity, signature assurance and non-repudiatability over Web data. Such features are especially important for documents that represent commitments such as contracts, price lists, and manifests. In view of recent Web technology developments, the proposed work will address the digital signing of documents (any Web resource addressable by a URI) using XML syntax. This capability is critical for a variety of electronic commerce applications, including payment tools.


The mission of this working group is to develop an XML compliant syntax used for representing the signature of Web resources and portions of protocol messages (anything referencable by a URI) and procedures for computing and verifying such signatures. Such signatures may be able to provide data integrity, authentication, and/or non-repudiatability. The meaning of the signature may be extensible by a set of semantics specified separately.


This effort is equally and strongly dependent on XML expertise and coordination, which is in the W3C, and Internet cryptographic expertise and coordination, which is in the Internet Engineering Task Force (IETF). Therefore, the working group will be a joint body operating simultaneously as an IETF WG and a W3C WG. Procedures may differ from the norm for either organization (IETF RFCs 2026 / 2418 & World Wide Web Consortium Process Document). Details are give in the sections below.


The core scope of this activity will be in specifying the necessary data model, syntax, and processing to bind a cryptographic signature to a resource in XML. The working group will focus on:

1. Creating a data model that permits XML-DSig to be an integral part of developing metadata and object model technologies.

2. Creating a extensible canonicalization framework. In addition, specify application requirements over canonicalization. All XML-DSig applications must be able to sign - at least - the binary byte stream. The group may also require applications to support XML syntax or Unicode canonicalization if those mechanisms are widely understood and necessary. This group will coordinate its requirements with activities delivering XML, RDF, or DOM canonicalization mechanisms.

3. Syntax and processing for XML signatures.

4. Document the WG's position on signature semantics. At the Chair's discretion the WG may develop a (small) set of signature semantics. Such a proposal would define common semantics relevant to signed assertions about Web resources and their relationships in a schema definition (XML/RDF) or link type definition (XLink).

5. Defining the charter for subsequent work once (1-4) has been achieved.


The following requirements must be met by the WG:

1. Define a simple signature XML syntax that is highly extensible. We wish to create a simple digital signature syntax that can be used with other application semantics (through XML-namespaces) so as to create arbitrarily sophisticated assertion capabilities.

2. Ensuring that applications can create and process composite/compound documents consisting of XML and non-XML data as well as for processing detached or external signature blocks and assertions.

3. XML-DSig must be coordinated with and use the work product of other mature XML technologies.

4. XML-DSig syntax expresses data model semantics; we do not require applications to make inferences on that data model.

5. Mandatory portions of the specification must be implemented in at least two independent implementations before being advanced to Proposed Standard.


The working group will not address the following issues:

1. Trust engines

2. Public key infrastructure

3. Trust management systems

4. XML schemas for certificates


It is hoped that the following applications being developed by members of the WG will provide a useful test of the completeness:

1. Internet Open Trading Protocol v2.0

2. [some document / web-page application TBD]

3. Financial Services Mark Up Language v2.0


This working group will deliver the following:

- - Informational RFC (W3C NOTE) further specifying the requirements and dependencies for the remaining deliverables.

- - Proposed Standard RFC (W3C Recommendation) that defines a highly extensible XML syntax and processing used for associating a signature with XML data without semantic specification but having provisions for the inclusion of such specification.

- - Optional Informational RFC (W3C NOTE) on signature semantics labeling and, if appropriate, an additional (small) set of signature semantics in a schema definition (XML/RDF) or link type definition (XLink).

- - Informational RFC (W3C NOTE) documenting a set of test cases for interoperability testing and a report on interoperability results.

- - If appropriate, charters for further work.


A central characteristic of this activity is its dependencies on other XML working groups. The WG chair will likely be a member of the W3C XML Coordination Group. During W3C Last Call, the Chair will procure reviews from the following W3C WGs before the specification will be advanced further:

1. XML Syntax/Core WG: Canonicalizing XML which involves finding a single or "canonical" version of every possible form of the same document by reducing white space, mapping quote marks to a standard form, etc. etc.) with a view to using that standard form for the purpose of applying digital signature technology.

2. XML Linking WG: The objective of the XML Linking Working Group is to design advanced, scalable, and maintainable hyperlinking and addressing functionality for XML

3. XML Schema WG: The XML Schema Working Group is addressing means for defining the structure, content and semantics of XML documents.

4. Metadata CG: The RDF Model and Syntax provides a uniform and interoperable means to exchange the metadata between programs and across the Web. Furthermore, RDF provides a means for publishing both a human-readable and a machine-understandable definition of the property set itself.


Working group members are expected to participate in an electronic mailing list, periodic teleconferences, and face-to-face meetings. The sole WG consensus venue is the mailing list.

Group Home Page:

In order to maintain shared context of the group and to provide access to the proceedings of the group, the Chair maintains a web page at http://www.w3.org/Signature.

Active participants are expected to have ready access to this page and be familiar with its contents.

Mailing List:

Participants must subscribe to and particiapte in the w3c-ietf-xmldsig@w3.org mailing list. The archive is http://lists.w3.org/Archives/Public/w3c-ietf-xmldsig.


There are expected to be teleconferences held every few weeks at a time set by the Chair. The exact frequency of calls will be determined by working group consensus.

The Chair is responsible for producing an agenda at least 24 hours in advance of each call, posting it along with the call details to the mailing list, and causing minutes of the call to be posted promptly after the call.

Face to Face Meetings:

The working group will have a two day face to face meeting in or near September 1999 and meet at the July and November 1999 IETF meetings and may have additional physical meetings by consensus of the WG. Meeting notice, advance agenda, and posting of minutes shall follow W3C timing rules.

Communication with the Public:

This working group is public.


WG documents will be dual published in both the IETF as Internet-Drafts or RFCs and in the W3C, via the web. Differing delays in the processes may cause skew in the appearance of a document in the two locations.

When a document is subject to a Last Call in both organizations (Working Group or IETF Last Call in the IETF, W3C Last Call or AC Review in the W3C) comments received in both venues must be considered and responded to. In effect, the Last Call period will be longer of the times allowed in the IETF and W3C.

The rough equivalence between document types in the IETF and W3C (and minimum length of time in that state) is as follows:


Working Group Internet Draft -- Working Draft

Informational RFC -- Note

Last Call (4w) -- Last Call (4w)

Proposed Standard RFC(6m) -- Candidate Recomendation(4w), Proposed Recommendation(6w)

Draft Standard RFC(4m) -- Recommendation

Full Standard RFC -- Recommendation

If a document is substantively changed such that it recycles to a lower status in either venue, the corresponding document classification in the other venue should also change.

IETF Last Calls for joint WG documents which are on the IETF standards track will be 4 weeks per the Variance section of RFC 2026.


The working group itself will operate by consensus as provided in the IETF rules.

Appeals from decisions by the working group chair may be taken using either the W3C or the IETF appeals mechanisms. It is expected that these mechanisms will coordinate and differences are not anticipated. Nevertheless, if and when the appeal mechanisms of the W3C and IETF come to irreconcilable decisions, the group will thereby cease to be a working group of either the W3C or the IETF and may not take further official action under the procedures of either organization without explicit rechartering.

Should either the W3C or the IETF unilaterally terminate the Working Group status so far as that organization is concerned, the WG will continue to be a working group of the other organization.


Working group members must disclose intellectual properties "that are reasonably and personally known" to be relevant to this WG in accordance with IETF (RFC2026) and W3C procedure; including notice and disclosure of such information to the WG, and the IETF Executive Director.


Participation in the working group is open. Participation is expected to take a minimum of 15% of the participants time. The XML-DSig WG will be co-chaired by Donald Eastlake III (Motorola) and Jospeh Reagle (W3C). Each co-chair is expected to devote 20% of his time to this activity.

W3C Team

The XML-DSig Staff Contact will be Joseph Reagle and his staff contact duties are expected to take 40% of his time. The staff contact is partly responsible to coordinating dependencies and requirements from the W3C Director and other activities. Further details on the Staff Contact and Chair roles can be found in the W3C Guidebook for Working Group Chairs.


Once established, the Working Group can decide to parallelize more tasks by forming subgroups. The Working Group can also decide to reschedule tasks that do not have to meet deadlines imposed by other groups. However, the schedule must fit into the total timeframe given below.

Also, document dates may not be rescheduled without notifying the W3C Domain leaders, the W3C director, and the IETF Area Director. Note that delay of deliverables can be a reason for the Working Group to be terminated.

The working group charter was updated in March 2000 as follows: (1) The duration of the working group has been extended by four months.

(2) The Signature Semantics document will not likey be produced -- its production was optional and at the discretion of the Chairs.

Goals and Milestones:

Jun 99


Submit first Requirements draft



Meet in Oslo Norway at IETF

Jul 99


Submit first Syntax and Processing Draft

Aug 99


Requirements document to Last Call for Informational RFC / W3C Final Working Draft



Meet during IETF in Washington DC

Nov 99


XML Signature Syntax and Processing document to Last Call as Proposed Standard / W3C Proposed Recommendation



WG recharters if appropriate

Jan 00


Submit Internet-Draft of interoperability test cases

Jan 00


Requirements document approved as Informational RFC

Feb 00


Signature Semantics document to Last Call as Proposed Standard / W3C Proposed Recommendation

Mar 00


Interoperability Test Cases and Results document to Last Call as Informational RFC / W3C NOTE

Mar 00


Meet during IETF in Adelaide

Apr 00


Submit Signature Syntax and Processing document to IESG for consideration as a Draft Standard RFC / W3C Candidate Recommendation

May 00


Signature Syntax and Processing specification to W3C Propose Recommendation

Jul 00


Signature Syntax and Processing specification to W3C Recommendation

Jul 00


WG recharters if appropriate


No Request For Comments

Current Meeting Report

None received.


None received.