Using DANE to Associate OpenPGP public keys with email addresses
draft-ietf-dane-openpgpkey-05

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Network Working Group                                         P. Wouters
Internet-Draft                                                   Red Hat
Intended status: Experimental                            August 28, 2015
Expires: February 29, 2016

    Using DANE to Associate OpenPGP public keys with email addresses
                     draft-ietf-dane-openpgpkey-05

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
   DNSSEC.

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
   working documents as Internet-Drafts.  The list of current Internet-
   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 February 29, 2016.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  The OPENPGPKEY Resource Record  . . . . . . . . . . . . . . .   3
     2.1.  The OPENPGPKEY RDATA component  . . . . . . . . . . . . .   4
       2.1.1.  The OPENPGPKEY RDATA content  . . . . . . . . . . . .   4
       2.1.2.  Reducing the Transferable Public Key size . . . . . .   5
     2.2.  The OPENPGPKEY RDATA wire format  . . . . . . . . . . . .   5
     2.3.  The OPENPGPKEY RDATA presentation format  . . . . . . . .   5
   3.  Location of the OPENPGPKEY record . . . . . . . . . . . . . .   5
   4.  Email address variants  . . . . . . . . . . . . . . . . . . .   6
   5.  Application use of OPENPGPKEY . . . . . . . . . . . . . . . .   7
     5.1.  Obtaining an OpenPGP key for a specific email address . .   7
     5.2.  Confirming the validity of an OpenPGP key . . . . . . . .   7
     5.3.  Verifying an unknown OpenPGP signature  . . . . . . . . .   7
   6.  OpenPGP Key size and DNS  . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
     7.1.  Response size . . . . . . . . . . . . . . . . . . . . . .   8
     7.2.  Email address information leak  . . . . . . . . . . . . .   8
     7.3.  Storage of OPENPGPKEY data  . . . . . . . . . . . . . . .   9
     7.4.  Forward security of OpenPGP versus DNSSEC . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  OPENPGPKEY RRtype . . . . . . . . . . . . . . . . . . . .  10
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     10.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Appendix A.  Generating OPENPGPKEY records  . . . . . . . . . . .  11
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   OpenPGP [RFC4880] public keys are used to encrypt or sign email
   messages and files.  To encrypt an email message, or verify a
   sender's OpenPGP signature, the email client or MTA needs to locate
   the recipient's OpenPGP public key.

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   OpenPGP clients have relied on centralized "well-known" key servers
   that are accessed using either the HTTP Keyserver Protocol [HKP]
   Alternatively, users need to manually browse a variety of different