Domain Keys Identified Mail (dkim)
|Name:||Domain Keys Identified Mail|
|Area:||Security Area (sec)|
|More info:||Additional DKIM Web Page|
Barry Leiba <email@example.com>
Internet mail protocols do not certify the validity of any
identification information associated with a message, including
the author's name and address. This limits the ability to
determine legitimate accountability for a message. It also limits
the ability to determine unauthorized uses of these identifiers.
The DKIM working group has produced two standards-track
specifications. The first allows a domain to take responsibility,
using digital signatures, for having taken part in the
transmission of an email message. The second allows a domain to
publish information about its practices in applying those
signatures. Taken together, these allow receiving domains to
ascertain responsibility for a message, and possibly to detect
some unauthorized assertions of authorship.
While the techniques specified by the DKIM working group will not
prevent fraud or spam, they can assist in efforts to establish a
basis for identifying actors that can be trusted. The
standards-track specifications do 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 discuss a reasonable set of
possible actions and strategies, and analyze their likely effects
on attacks and on normal email delivery.
+++ Previous Work +++
The previously chartered deliverables for the DKIM working group
have been completed. To provide background, we list them here:
* An informational RFC presenting a detailed threat analysis of,
and security requirements for, DKIM. (RFC 4686)
* A standards-track specification for DKIM signature and
verification. (RFC 4871, updated by RFC 5672)
* A standards-track specification for DKIM policy handling.
* 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. (RFC 5585 and
draft-ietf-dkim-deployment, in its final stages)
(One previously chartered deliverable, a standards-track
specification for DKIM DNS Resource Record(s), was dropped by
agreement between the working group and the Area Directors.)
+++ New Work +++
The working group is now ready to switch its focus to refining and
advancing the DKIM protocols. The current deliverables for the
DKIM working group are these:
1. Advance the base DKIM protocol (RFC 4871) to Draft Standard.
This is the first priority for the working group.
2. Collect data on the deployment, interoperability, and
effectiveness of the base DKIM protocol, with consideration
toward updating the working group's informational documents.
3. Collect data on the deployment, interoperability, and
effectiveness of the Author Domain Signing Practices protocol
(RFC 5617), and determine if/when it's ready to advance on the
standards track. Update it at Proposed Standard, advance it to
Draft Standard, deprecate it, or determine another disposition,
4. Taking into account the data collected in (2) and (3), update
the overview and deployment/operations documents. These are
considered living documents, and should be updated periodically,
as we have more real-world experience.
5. Consider issues related to mailing lists, beyond what is
already documented. This includes considerations for mailing
list software that supports or intends to support DKIM, as well
as considerations for DKIM/ADSP deployment in the presence of
mailing lists that do not have such support. Include
recommendations in the informational documents, or produce a
new informational document about mailing-list considerations.
+++ What's Out Of Scope +++
As before, several related topics remain 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
* 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
* 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
WG last call on DKIM threats and security requirements
WG last call on DKIM signature specification
WG last call on SSP requirements
WG adoption of SSP protocol draft
DKIM base (RFC 4871) interoperability report
WG last call on update to RFC4871 if necessary for advancement to DS
WG last call on an I-D addressing issues related to mailing lists
WG last call on an I-D detailing deployment and effectiveness data for DKIM base
WG last call on an I-D detailing deployment and effectiveness data for ADSP
Update overview and deployment informational RFCs as appropriate, and/or produce one or more new informational RFCs from information obtained above