XML Digital Signatures
XML Digital Signatures WG
||XML Digital Signatures
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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
JOINT IETF / W3C COORDINATION:
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
Consortium Process Document). Details are give in the sections below.
The core scope of this activity will be in specifying the necessary
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
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
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
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
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
- - 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.
COORDINATION WITH OTHER W3C GROUPS:
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
from the following W3C WGs before the specification will be advanced
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
Active participants are expected to have ready access to this page and
be familiar with its contents.
Participants must subscribe to and particiapte in the
email@example.com mailing list. The archive is
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
Communication with the Public:
This working group is public.
IETF / W3C PROCESS SYNCHRONIZATION:
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
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:
IETF -- W3C
Working Group Internet Draft -- Working Draft
Informational RFC -- Note
Last Call (4w) -- Last Call (4w)
Proposed Standard RFC(6m) -- Candidate Recomendation(4w),
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
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.
DECISON PROCEDURES AND APPEALS:
The working group itself will operate by consensus as provided in the
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
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
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
with IETF (RFC2026) and W3C procedure; including notice and disclosure
of such information to the WG, <firstname.lastname@example.org> and the IETF
Participation in the working group is open. Participation is expected
to take a minimum of 15% of the participants time. The XML-DSig WG
be co-chaired by Donald Eastlake III (Motorola) and Jospeh Reagle
Each co-chair is expected to devote 20% of his time to this activity.
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
Once established, the Working Group can decide to parallelize more
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
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.