Using a DNS SRV Record to Locate an X.509 Certificate Store
draft-bhjl-x509-srv-01

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Network Working Group                                        B. Haberman
Internet-Draft                                                   JHU APL
Intended status: Standards Track                               J. Levine
Expires: January 20, 2017                           Taughannock Networks
                                                           July 19, 2016

      Using a DNS SRV Record to Locate an X.509 Certificate Store
                         draft-bhjl-x509-srv-01

Abstract

   This document describes a method to allow parties to locate X.509
   certificate stores with Domain Name System Service records in order
   to retrieve certificates and certificate revocation lists.  The
   primary purpose of such retrievals is to facilitate the association
   of X.509 and PGP public keys with e-mail addresses to allow for
   encrypted e-mail exchanges.

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
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   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 January 20, 2017.

Copyright Notice

   Copyright (c) 2016 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
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   (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

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Service Record Format . . . . . . . . . . . . . . . . . . . .   2
   3.  Certificate Store Queries . . . . . . . . . . . . . . . . . .   3
   4.  Name Matching . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Certificate Validation  . . . . . . . . . . . . . . . . . . .   4
   6.  Certificate use and cacheing  . . . . . . . . . . . . . . . .   4
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Certificates service  . . . . . . . . . . . . . . . . . .   5
     8.2.  Smimeca service . . . . . . . . . . . . . . . . . . . . .   6
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   10. Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   X.509 and PGP public keys can be used to encrypt or sign e-mail
   messages.  In order to verify a sender's signature or encrypt an
   e-mail, the e-mail client needs to locate the appropriate public key.
   The X.509-based Public Key Infrastructure (PKI) [RFC5280] provides
   the necessary services to allow for the retrieval of certificates and
   certificate revocation lists, but lacks the discovery mechanism
   needed to associate e-mail domains with specific PKI servers.

   This document specifies an approach that uses a Domain Name System
   (DNS) Service Record (SRV) that allows mail service providers to
   advertise the X.509 or PGP certificate store [RFC4387] that contains
   certificates and certificate revocation lists for their e-mail users.
   Additionally, this document specifies the appropriate query strings
   to use when accessing the certificate store.

   The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
   "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119].

2.  Service Record Format

   The general format of a DNS SRV record is documented in [RFC2782] as:

        _Service._Proto.Name TTL Class SRV Priority Weight Port Target

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   To support the advertisement of an X.509 certificate store, service
   providers will construct an SRV record with the appropriate
   parameters, as described in [RFC4387], section 3.2.  An example of