DomainKeys Identified Mail (DKIM) Authorized Third-Party Signatures
RFC 6541

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 16

Internet Engineering Task Force (IETF)                      M. Kucherawy
Request for Comments: 6541                               Cloudmark, Inc.
Category: Experimental                                     February 2012
ISSN: 2070-1721

  DomainKeys Identified Mail (DKIM) Authorized Third-Party Signatures

Abstract

   This experimental specification proposes a modification to DomainKeys
   Identified Mail (DKIM) allowing advertisement of third-party
   signature authorizations that are to be interpreted as equivalent to
   a signature added by the administrative domain of the message's
   author.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  This document is a product of the Internet Engineering
   Task Force (IETF).  It represents the consensus of the IETF
   community.  It has received public review and has been approved for
   publication by the Internet Engineering Steering Group (IESG).  Not
   all documents approved by the IESG are a candidate for any level of
   Internet Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6541.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Kucherawy                     Experimental                      [Page 1]
RFC 6541                  DKIM ATPS Experiment             February 2012

Table of Contents

   1. Introduction ....................................................2
   2. Definitions .....................................................3
      2.1. Key Words ..................................................3
      2.2. Email Architecture Terminology .............................3
   3. Roles and Scope .................................................3
   4. Queries and Replies .............................................4
      4.1. Hash Selection .............................................4
      4.2. Extension to DKIM ..........................................5
      4.3. ATPS Query Details .........................................5
      4.4. ATPS Reply Details .........................................7
   5. Interpretation ..................................................8
   6. Relationship to ADSP ............................................8
   7. Experiment Process ..............................................8
   8. IANA Considerations .............................................9
      8.1. ATPS Tag Registry ..........................................9
      8.2. Email Authentication Methods Registry Update ..............10
      8.3. Email Authentication Result Names Registry Update .........10
      8.4. DKIM Signature Tag Specifications Registry ................12
   9. Security Considerations ........................................12
      9.1. Hash Selection ............................................12
      9.2. False Privacy .............................................12
      9.3. Transient Security Failures ...............................13
      9.4. Load on the DNS ...........................................13
   10. References ....................................................13
      10.1. Normative References .....................................13
      10.2. Informative References ...................................14
   Appendix A. Example Query and Reply ...............................15
   Appendix B. Choice of DNS RR Type .................................15
   Appendix C. Acknowledgements ......................................16

1.  Introduction

   [DKIM] defines a mechanism for transparent domain-level signing of
   messages for the purpose of declaring that a particular
   ADministrative Management Domain (ADMD) takes some responsibility for
   a message.

   DKIM, however, deliberately makes no binding between the DNS domain
   of the Signer and any other identity found in the message.  Despite
   this, there is an automatic human perception that an Author Domain
   Signature (one for which the RFC5322.From domain matches the DNS
   domain of the Signer) is more valuable or trustworthy than any other.

   To enable a third party to apply DKIM signatures to messages, the