ACME Account Key Binding via CAA Records
draft-landau-acme-caa-00

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Last updated 2016-04-21
Replaced by draft-ietf-acme-caa
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ACME Working Group                                             H. Landau
Internet-Draft                                            April 21, 2016
Intended status: Informational
Expires: October 23, 2016

                ACME Account Key Binding via CAA Records
                        draft-landau-acme-caa-00

Abstract

   The ACME protocol provides a means for hosts to automatically request
   and obtain X.509 certificates from certificate authorities.
   Certification authorities which implement ACME may also choose to
   implement the CAA DNS record, which allows a domain to communicate
   issuance policy to CAs.  The CAA specification alone allows a domain
   to define policy with CA-level granularity.  However, the CAA
   specification also provides facilities for extension to admit more
   granular, CA-specific policy.  This specification defines such a
   parameter.

Status of This Memo

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

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   This Internet-Draft will expire on October 23, 2016.

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

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   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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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Extensions to the CAA Record  . . . . . . . . . . . . . . . .   2
     3.1.  acme-ak Parameter . . . . . . . . . . . . . . . . . . . .   2
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
     4.1.  DNSSEC  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     4.2.  Authorization Freshness . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   This specification defines a parameter for the 'issue' and
   'issuewild' properties of the Certification Authority Authorization
   (CAA) DNS resource record [RFC6844], allowing authorization conferred
   by a CAA policy to be restricted to specific ACME
   [I-D.ietf-acme-acme] accounts.  The accounts are identified by
   account key thumbprint.

2.  Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119
   [RFC2119] and indicate requirement levels for compliant ACME-CAA
   implementations.

3.  Extensions to the CAA Record

3.1.  acme-ak Parameter

   A CAA parameter "acme-ak" is defined for the 'issue' and 'issuewild'
   properties defined by [RFC6844].  The value of this parameter, if
   specified, MUST be the base64url [RFC4648] encoding (without padding)
   of the JWK thumbprint [RFC7517] of the ACME account key
   [I-D.ietf-acme-acme].

   If an ACME server finds multiple CAA records pertaining to it (i.e.,
   having property 'issue' or 'issuewild' as applicable and a domain

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   that the ACME server recognises as its own) with different "acme-ak"
   parameters, the ACME server MUST NOT consider the CAA record set to
   authorize issuance unless at least one of the specified account key
   thumbprints matches the requesting ACME account key.  A property
   without an "acme-ak" parameter matches any account key.  A property
   with an invalid "acme-ak" parameter (i.e. not 43 characters long or
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