Using DANE to Associate OpenPGP public keys with email addresses
draft-ietf-dane-openpgpkey-06

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Network Working Group                                         P. Wouters
Internet-Draft                                                   Red Hat
Intended status: Experimental                           October 20, 2015
Expires: April 22, 2016

    Using DANE to Associate OpenPGP public keys with email addresses
                     draft-ietf-dane-openpgpkey-06

Abstract

   OpenPGP is a message format for email (and file) encryption that
   lacks a standardized lookup mechanism to securely obtain OpenPGP
   public keys.  This document specifies a method for publishing and
   locating OpenPGP public keys in DNS for a specific email address
   using a new OPENPGPKEY DNS Resource Record.  Security is provided via
   Secure DNS, however the OPENPGPKEY record is not a replacement for
   verification of authenticity via the "Web of Trust" or manual
   verification.  The OPENPGPKEY record can be used to encrypt an email
   that would otherwise have to be send unencrypted.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 22, 2016.

Copyright Notice

   Copyright (c) 2015 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

Wouters                  Expires April 22, 2016                 [Page 1]
Internet-Draft        DANE for OpenPGP public keys          October 2015

   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Experiment goal . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  The OPENPGPKEY Resource Record  . . . . . . . . . . . . . . .   4
     2.1.  The OPENPGPKEY RDATA component  . . . . . . . . . . . . .   4
       2.1.1.  The OPENPGPKEY RDATA content  . . . . . . . . . . . .   5
       2.1.2.  Reducing the Transferable Public Key size . . . . . .   5
     2.2.  The OPENPGPKEY RDATA wire format  . . . . . . . . . . . .   6
     2.3.  The OPENPGPKEY RDATA presentation format  . . . . . . . .   6
   3.  Location of the OPENPGPKEY record . . . . . . . . . . . . . .   6
   4.  Email address variants  . . . . . . . . . . . . . . . . . . .   7
   5.  Application use of OPENPGPKEY . . . . . . . . . . . . . . . .   7
     5.1.  Obtaining an OpenPGP key for a specific email address . .   8
     5.2.  Confirming the validity of an OpenPGP key . . . . . . . .   8
     5.3.  Public Key UIDs and query names . . . . . . . . . . . . .   8
   6.  OpenPGP Key size and DNS  . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
     7.1.  MTA behaviour . . . . . . . . . . . . . . . . . . . . . .  10
     7.2.  MUA behaviour . . . . . . . . . . . . . . . . . . . . . .  11
     7.3.  Email client behaviour  . . . . . . . . . . . . . . . . .  11
     7.4.  Response size . . . . . . . . . . . . . . . . . . . . . .  11
     7.5.  Email address information leak  . . . . . . . . . . . . .  11
     7.6.  Storage of OPENPGPKEY data  . . . . . . . . . . . . . . .  12
     7.7.  Security of OpenPGP versus DNSSEC . . . . . . . . . . . .  12
   8.  Implementation Status . . . . . . . . . . . . . . . . . . . .  12
     8.1.  The GNU Privacy Guard (GNUpg) . . . . . . . . . . . . . .  13
     8.2.  hash-slinger  . . . . . . . . . . . . . . . . . . . . . .  14
     8.3.  openpgpkey-milter . . . . . . . . . . . . . . . . . . . .  14
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
     9.1.  OPENPGPKEY RRtype . . . . . . . . . . . . . . . . . . . .  15
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  15
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  15
     11.2.  Informative References . . . . . . . . . . . . . . . . .  16