2.7.2 Domain Keys Identified Mail (dkim)

NOTE: This charter is a snapshot of the 69th IETF Meeting in Chicago, IL USA. It may now be out-of-date.
In addition to this official charter maintained by the IETF Secretariat, there is additional information about this working group on the Web at:

       Additional DKIM Web Page

Last Modified: 2007-04-02

Chair(s):

Stephen Farrell <stephen.farrell@cs.tcd.ie>
Barry Leiba <leiba@watson.ibm.com>

Security Area Director(s):

Tim Polk <tim.polk@nist.gov>
Sam Hartman <hartmans-ietf@mit.edu>

Security Area Advisor:

Tim Polk <tim.polk@nist.gov>

Mailing Lists:

General Discussion: ietf-dkim@mipassoc.org
To Subscribe: http://mipassoc.org/mailman/listinfo/ietf-dkim
Archive: http://mipassoc.org/pipermail/ietf-dkim/

Description of Working Group:

The Internet mail protocols and infrastructure allow mail sent from one
domain to purport to be from another. While there are sometimes
legitimate reasons for doing this, it has become a source of general
confusion, as well as a mechanism for fraud and for distribution of
spam (when done illegitimately, it's called "spoofing"). The DKIM
working group will produce standards-track specifications that allow a
domain to take responsibility, using digital signatures, for having
taken part in the transmission of an email message and to
publish "policy" information about how it applies those signatures.
Taken together, these will assist receiving domains in detecting (or
ruling out) certain forms of spoofing as it pertains to the signing
domain.

The DKIM working group will produce a summary of the threats that are
addressed by the proposed standards-track specifications, while
acknowledging their limitations and scope. The DKIM working group will
also produce security requirements to guide their efforts, and will
analyze the impact on senders and receivers who are not using DKIM,
particularly any cases in which mail may be inappropriately labeled as
suspicious or spoofed.

While the techniques specified by the DKIM working group will not
prevent fraud or spam, they will provide a tool for defense against
them by assisting receiving domains in detecting some spoofing of
known domains. The standards-track specifications will not mandate any
particular action by the receiving domain when a signature fails to
validate. That said, with the understanding that guidance is necessary
for implementers, the DKIM documents should discuss a reasonable set
of possible actions and strategies, and analyze their likely effects
on attacks and on normal email delivery. The DKIM working group will
not attempt to establish requirements for trust relationships between
domains nor to specify reputation or accreditation systems.

The DKIM working group will consider mailing-list behaviour that is
currently deemed acceptable, will make every effort to allow such
mailing lists to continue to operate in a DKIM environment, and will
provide a plan for smooth transition of mailing lists that fail to
operate. The specifications will also advise mailing lists on how to
take advantage of DKIM if they should choose to do so.

The signatures will use public-key cryptography and will be based on
domain name identifiers. Public keys needed to validate the signatures
will be stored in the responsible identity's DNS hierarchy. The
specifications will be based on the following Internet Drafts:

  * draft-fenton-dkim-threats
  * draft-allman-dkim-base
  * draft-allman-dkim-ssp

These documents represent experimentation and consensus from a number
of designers and early implementors.

Experimentation has resulted in Internet deployment of these
specifications. Although not encouraged, non-backwards-compatible
changes to these specifications will be acceptable if the DKIM working
group determines that the changes are required to meet the group's
technical objectives.

The resulting protocols must meet typical criteria for success. In
addition to security, these include usability, scalability, ease of
deployment, and cryptographic algorithm independence.

To prevent this task from becoming unwieldy, several related topics are
considered out of scope for the DKIM working group. These topics
include:

* Reputation and accreditation systems. While we expect these to add
  value to what is defined by the DKIM working group, their development
  will be separate, and is out of scope for the DKIM working group.

* Message content encryption.

* Additional key management protocols or infrastructure.

* Signatures that are intended to make long-term assertions beyond the
  expected transit time of a message from originator to recipient,
  which is normally only a matter of a few days at most.

* Signatures that attempt to make strong assertions about the identity
  of the message author, and details of user-level signing of messages
  (as distinguished from domain-level keys that are restricted to
  specific users).

* Duplication of prior work in signed email, including S/MIME and
  OpenPGP.

Once the primary goals are met, the DKIM working group may also study
whether to adopt a work item for specifying a common mechanism to
communicate the results of message verification to the message
recipient. The generation of a standards-track specification on this
topic will require an update to the DKIM working group charter.

The deliverables for the DKIM working group are these:

* An informational RFC presenting a detailed threat analysis of, and
  security requirements for, DKIM. IESG approval of this document is
  a prerequisite for the submission of the standards-track
  specifications.

* A standards-track specification for DKIM signature and verification.

* A standards-track specification for DKIM policy handling.

* A standards-track specification for DKIM DNS Resource Record(s).

* An informational RFC providing an overview of DKIM and how it can
  fit into overall messaging systems, how it relates to other IETF
  message signature technologies, implementation and migration
  considerations, and outlining potential DKIM applications and
  future extensions.

Goals and Milestones:

Done  WG last call on DKIM threats and security requirements
Done  WG last call on DKIM signature specification
Mar 2007  WG last call on SSP requirements
May 2007  WG adoption of SSP protocol draft
Nov 2007  WG last call on SSP protocol
Nov 2007  WG last call on overview document

Internet-Drafts:

  • draft-ietf-dkim-overview-05.txt
  • draft-ietf-dkim-ssp-requirements-04.txt
  • draft-ietf-dkim-ssp-00.txt

    Request For Comments:

    RFCStatusTitle
    RFC4686 I Analysis of Threats Motivating DomainKeys Identified Mail (DKIM)
    RFC4871 PS DomainKeys Identified Mail (DKIM) Signatures

    Meeting Minutes


    Slides

    Introduction
    DKIM Sender Signing Practices
    DKIM overview document