Domain Keys Identified Mail (dkim) ---------------------------------- Charter Last Modified: 2007-04-02 Current Status: Active Working Group Chair(s): Stephen Farrell Barry Leiba Security Area Director(s): Tim Polk Sam Hartman Security Area Advisor: Tim Polk 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: Posted Revised I-D Title ------ ------- -------------------------------------------- Jun 2006 Jun 2007 DomainKeys Identified Mail (DKIM) Message Signing Service Overview Aug 2006 Apr 2007 Requirements for a DKIM Signing Practices Protocol Request For Comments: RFC Stat Published Title ------- -- ----------- ------------------------------------ RFC4686 I Sep 2006 Analysis of Threats Motivating DomainKeys Identified Mail (DKIM) RFC4871 PS May 2007 DomainKeys Identified Mail (DKIM) Signatures