ACME for Subdomains
draft-friel-acme-subdomains-00

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Last updated 2019-10-23
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Network Working Group                                           O. Friel
Internet-Draft                                                 R. Barnes
Intended status: Standards Track                                   Cisco
Expires: April 25, 2020                                     T. Hollebeek
                                                                DigiCert
                                                        October 23, 2019

                          ACME for Subdomains
                     draft-friel-acme-subdomains-00

Abstract

   This document outlines how ACME can be used by a client to obtain a
   certificate for a subdomain identifier from a certificate authority.
   The client has fulfilled a challenge against a parent domain but does
   not need to fulfil a challenge against the explicit subdomain as
   certificate authority policy allows issuance of the subdomain
   certificate without explicit subdomain ownership proof.

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 April 25, 2020.

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   Copyright (c) 2019 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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   (https://trustee.ietf.org/license-info) in effect on the date of
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   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
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  ACME Workflow and Identifier Requirements . . . . . . . . . .   3
   4.  ACME Issuance of Subdomain Certificates . . . . . . . . . . .   4
     4.1.  newOrder and newAuthz Handling  . . . . . . . . . . . . .   5
     4.2.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Directory Object Metadata Fields Registry . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  Informative References  . . . . . . . . . . . . . . . . . . .   8
   Appendix A.  CA Browser Forum Baseline Requirements . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   ACME [RFC8555] defines a protocol that a certificate authority (CA)
   and an applicant can use to automate the process of domain name
   ownership validation and X.509 (PKIX) certificate issuance.  The
   protocol is rich and flexible and enables multiple use cases that are
   not immediately obvious from reading the specification.

   This document explicitly outlines how ACME can be used to issue
   subdomain certificates, without requiring the ACME client to
   explicitly fulfil an ownership challenge against the subdomain
   identifiers - the ACME client need only fulfil an ownership challenge
   against a parent domain identifier.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   The following terms are used in this document:

   o  CA: Certificate Authority

   o  CSR: Certificate Signing Request

   o  FQDN: Fully Qualified Domain Name

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3.  ACME Workflow and Identifier Requirements

   A typical ACME workflow for issuance of certificates is as follows:

   1.  client POSTs a newOrder request that contains a set of
       "identifiers"

   2.  server replies with a set of "authorizations" and a "finalize"
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