[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02

Network Working Group                                           O. Friel
Internet-Draft                                                 R. Barnes
Intended status: Informational                                     Cisco
Expires: April 26, 2020                                   R. Shekh-Yusef
                                                                   Avaya
                                                        October 24, 2019


                           ACME Integrations
                    draft-friel-acme-integrations-02

Abstract

   This document outlines multiple advanced use cases and integrations
   that ACME facilitates without any modifications or enhancements
   required to the base ACME specification.  The use cases include ACME
   integration with EST, BRSKI and TEAP.

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 https://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 26, 2020.

Copyright Notice

   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
   Provisions Relating to IETF Documents
   (https://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




Friel, et al.            Expires April 26, 2020                 [Page 1]


Internet-Draft              ACME-INTEGRATIONS               October 2019


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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  ACME Integration with EST . . . . . . . . . . . . . . . . . .   3
   4.  ACME Integration with BRSKI . . . . . . . . . . . . . . . . .   6
   5.  ACME Integration with BRSKI Default Cloud Registrar . . . . .   8
   6.  ACME Integration with TEAP  . . . . . . . . . . . . . . . . .  10
   7.  ACME Integration with TEAP-BRSKI  . . . . . . . . . . . . . .  13
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   10. Informative References  . . . . . . . . . . . . . . . . . . .  16
   Appendix A.  Comments . . . . . . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

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 multiple advanced ACME use cases
   including:

   o  ACME integration with EST [RFC7030]

   o  ACME integration with BRSKI
      [I-D.ietf-anima-bootstrapping-keyinfra]

   o  ACME integration with BRSKI Default Cloud Registrar
      [I-D.friel-anima-brski-cloud]

   o  ACME integration with TEAP [RFC7170]

   o  ACME integration with TEAP-BRSKI [I-D.lear-eap-teap-brski]

   The integrations with EST, BRSKI (which is based upon EST), and TEAP
   enable automated certificate enrolment for devices.  ACME for
   subdomains [I-D.friel-acme-subdomains] outlines how ACME can be used
   by a client to obtain a certificate for a subdomain identifier from a
   certificate authority where client has fulfilled a challenge against
   a parent domain but does not need to fulfil a challenge against the
   explicit subdomain.  This is a useful optimisation when ACME is used
   to issue certificates for large numbers of devices as it reduces the



Friel, et al.            Expires April 26, 2020                 [Page 2]


Internet-Draft              ACME-INTEGRATIONS               October 2019


   domain ownership proof traffic (DNS or HTTP) and ACME traffic
   overhead, but is not a necessary requirement.

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  BRSKI: Bootstrapping Remote Secure Key Infrastructures
      [I-D.ietf-anima-bootstrapping-keyinfra]

   o  CA: Certificate Authority

   o  CMC: Certificate Management over CMS

   o  CSR: Certificate Signing Request

   o  EST: Enrollment over Secure Transport [RFC7030]

   o  FQDN: Fully Qualified Domain Name

   o  RA: PKI Registration Authority

   o  TEAP: Tunneled Extensible Authentication Protocol [RFC7170]

3.  ACME Integration with EST

   EST [RFC7030] defines a mechanism for clients to enroll with a PKI
   Registration Authority by sending CMC messages over HTTP.  EST
   section 1 states:

   "Architecturally, the EST service is located between a Certification
   Authority (CA) and a client.  It performs several functions
   traditionally allocated to the Registration Authority (RA) role in a
   PKI."

   EST section 1.1 states that:

   "For certificate issuing services, the EST CA is reached through the
   EST server; the CA could be logically "behind" the EST server or
   embedded within it."





Friel, et al.            Expires April 26, 2020                 [Page 3]


Internet-Draft              ACME-INTEGRATIONS               October 2019


   When the CA is logically "behind" the EST RA, EST does not specify
   how the RA communicates with the CA.  EST section 1 states:

   "The nature of communication between an EST server and a CA is not
   described in this document."

   This section outlines how ACME could be used for communication
   between the EST RA and the CA.  The example call flow leverages
   [I-D.friel-acme-subdomains] and shows the RA proving ownership of a
   parent domain, with individual client certificates being subdomains
   under that parent domain.  This is an optimisation that reduces DNS
   and ACME traffic overhead.  The RA could of course prove ownership of
   every explicit client certificate identifier.

   The call flow illustrates the client calling the EST /csrattrs API
   before calling the EST /simpleenroll API.  This enables the EST
   server to indicate to the client what attributes it expects the
   client to include in the CSR request send in the /simpleenroll API.
   For example, EST servers could use this mechanism to tell the client
   what fields to include in the CSR Subject and Subject Alternative
   Name fields.

   +--------+             +--------+             +------+     +-----+
   | Pledge |             | EST RA |             | ACME |     | DNS |
   +--------+             +--------+             +------+     +-----+
       |                      |                      |           |
                  STEP 1: Pre-Authorization of parent domain
       |                      |                      |           |
       |                      | POST /newAuthz       |           |
       |                      |  "domain.com"        |           |
       |                      |--------------------->|           |
       |                      |                      |           |
       |                      | 201 authorizations   |           |
       |                      |<---------------------|           |
       |                      |                      |           |
       |                      | Publish DNS TXT      |           |
       |                      | "domain.com"         |           |
       |                      |--------------------------------->|
       |                      |                      |           |
       |                      | POST /challenge      |           |
       |                      |--------------------->|           |
       |                      |                      | Verify    |
       |                      |                      |---------->|
       |                      | 200 status=valid     |           |
       |                      |<---------------------|           |
       |                      |                      |           |
       |                      | Delete DNS TXT       |           |
       |                      | "domain.com"         |           |



Friel, et al.            Expires April 26, 2020                 [Page 4]


Internet-Draft              ACME-INTEGRATIONS               October 2019


       |                      |--------------------------------->|
       |                      |                      |           |
                  STEP 2: Pledge enrolls against RA
       |                      |                      |           |
       | GET /csrattrs        |                      |           |
       |--------------------->|                      |           |
       |                      |                      |           |
       | 200 OK               |                      |           |
       | SEQUENCE {AttrOrOID} |                      |           |
       | SAN OID:             |                      |           |
       | "pledgeid.domain.com"|                      |           |
       |<---------------------|                      |           |
       |                      |                      |           |
       | POST /simpleenroll   |                      |           |
       | PCSK#10 CSR          |                      |           |
       | "pledgeid.domain.com"|                      |           |
       |--------------------->|                      |           |
       |                      |                      |           |
       | 202 Retry-After      |                      |           |
       |<---------------------|                      |           |
       |                      |                      |           |
                  STEP 3: RA places ACME order
       |                      |                      |           |
       |                      | POST /newOrder       |           |
       |                      | "pledgeid.domain.com"|           |
       |                      |--------------------->|           |
       |                      |                      |           |
       |                      | 201 status=ready     |           |
       |                      |<---------------------|           |
       |                      |                      |           |
       |                      | POST /finalize       |           |
       |                      | PKCS#10 CSR          |           |
       |                      | "pledgeid.domain.com"|           |
       |                      |--------------------->|           |
       |                      |                      |           |
       |                      | 200 OK status=valid  |           |
       |                      |<---------------------|           |
       |                      |                      |           |
       |                      | POST /certificate    |           |
       |                      |--------------------->|           |
       |                      |                      |           |
       |                      | 200 OK               |           |
       |                      | PEM                  |           |
       |                      | "pledgeid.domain.com"|           |
       |                      |<---------------------|           |
       |                      |                      |           |
                  STEP 4: Pledge retries enroll
       |                      |                      |           |



Friel, et al.            Expires April 26, 2020                 [Page 5]


Internet-Draft              ACME-INTEGRATIONS               October 2019


       | POST /simpleenroll   |                      |           |
       | PCSK#10 CSR          |                      |           |
       | "pledgeid.domain.com"|                      |           |
       |--------------------->|                      |           |
       |                      |                      |           |
       | 200 OK               |                      |           |
       | PKCS#7               |                      |           |
       | "pledgeid.domain.com"|                      |           |
       |<---------------------|                      |           |

4.  ACME Integration with BRSKI

   BRSKI [I-D.ietf-anima-bootstrapping-keyinfra] is based upon EST
   [RFC7030] and defines how to autonomically bootstrap PKI trust
   anchors into devices via means of signed vouchers.  EST certificate
   enrollment may then optionally take place after trust has been
   established.  BRKSI voucher exchange and trust establishment are
   based on EST extensions and the certificate enrollment part of BRSKI
   is fully based on EST.  Similar to EST, BRSKI does not define how the
   EST RA communicates with the CA.  Therefore, the mechanisms outlined
   in the previous section for using ACME as the communications protocol
   between the EST RA and the CA are equally applicable to BRSKI.

   The following call flow shows how ACME may be integrated into a full
   BRSKI voucher plus EST enrollment workflow.  For brevity, it assumes
   that the EST RA has previously proven ownership of a parent domain
   and that pledge certificate identifiers are a subdomain of that
   parent domain.  The domain ownership exchanges between the RA, ACME
   and DNS are not shown.  Similarly, not all BRSKI interactions are
   shown and only the key protocol flows involving voucher exchange and
   EST enrollment are shown.

   Similar to the EST section above, the client calls EST /csrattrs API
   before calling the EST /cimpleenroll API.  This enables the server to
   indicate what fields the pledge should include in the CSR that the
   client sends in the /simpleenroll API.

   +--------+             +--------+             +------+     +------+
   | Pledge |             | EST RA |             | ACME |     | MASA |
   +--------+             +--------+             +------+     +------+
       |                      |                      |           |
                  NOTE: Pre-Authorization of "domain.com" is complete
       |                      |                      |           |
                  STEP 1: Pledge requests Voucher
       |                      |                      |           |
       | POST /requestvoucher |                      |           |
       |--------------------->|                      |           |
       |                      | POST /requestvoucher |           |



Friel, et al.            Expires April 26, 2020                 [Page 6]


Internet-Draft              ACME-INTEGRATIONS               October 2019


       |                      |--------------------------------->|
       |                      |                      |           |
       |                      | 200 OK Voucher       |           |
       |                      |<---------------------------------|
       | 200 OK Voucher       |                      |           |
       |<---------------------|                      |           |
       |                      |                      |           |
                  STEP 2: Pledge enrolls against RA
       |                      |                      |           |
       | GET /csrattrs        |                      |           |
       |--------------------->|                      |           |
       |                      |                      |           |
       | 200 OK               |                      |           |
       | SEQUENCE {AttrOrOID} |                      |           |
       | SAN OID:             |                      |           |
       | "pledgeid.domain.com"|                      |           |
       |<---------------------|                      |           |
       |                      |                      |           |
       | POST /simpleenroll   |                      |           |
       | PCSK#10 CSR          |                      |           |
       | "pledgeid.domain.com"|                      |           |
       |--------------------->|                      |           |
       |                      |                      |           |
       | 202 Retry-After      |                      |           |
       |<---------------------|                      |           |
       |                      |                      |           |
                  STEP 3: RA places ACME order
       |                      |                      |           |
       |                      | POST /newOrder       |           |
       |                      | "pledgeid.domain.com"|           |
       |                      |--------------------->|           |
       |                      |                      |           |
       |                      | 201 status=ready     |           |
       |                      |<---------------------|           |
       |                      |                      |           |
       |                      | POST /finalize       |           |
       |                      | PKCS#10 CSR          |           |
       |                      | "pledgeid.domain.com"|           |
       |                      |--------------------->|           |
       |                      |                      |           |
       |                      | 200 OK status=valid  |           |
       |                      |<---------------------|           |
       |                      |                      |           |
       |                      | POST /certificate    |           |
       |                      |--------------------->|           |
       |                      |                      |           |
       |                      | 200 OK               |           |
       |                      | PEM                  |           |



Friel, et al.            Expires April 26, 2020                 [Page 7]


Internet-Draft              ACME-INTEGRATIONS               October 2019


       |                      | "pledgeid.domain.com"|           |
       |                      |<---------------------|           |
       |                      |                      |           |
                  STEP 4: Pledge retries enroll
       |                      |                      |           |
       | POST /simpleenroll   |                      |           |
       | PCSK#10 CSR          |                      |           |
       | "pledgeid.domain.com"|                      |           |
       |--------------------->|                      |           |
       |                      |                      |           |
       | 200 OK               |                      |           |
       | PKCS#7               |                      |           |
       | "pledgeid.domain.com"|                      |           |
       |<---------------------|                      |           |

5.  ACME Integration with BRSKI Default Cloud Registrar

   BRSKI Cloud Registrar [I-D.friel-anima-brski-cloud] specifies the
   behaviour of a BRSKI Cloud Registrar, and how a pledge can interact
   with a BRSKI Cloud Registrar when bootstrapping.  Similar to the
   local domain registrar BRSKI flow, ACME can be easily integrated with
   a cloud registrar bootstrap flow.

   BRSKI cloud registrar is flexible and allows for multiple different
   local domain discovery and redirect scenarios.  In the example
   illustrated here, the extension to [RFC8366] Vouchers which is
   defined in [[TODO ID-TBD]] and allows the specification of a
   bootstrap DNS domain is leveraged.  This extension allows the cloud
   registrar to specify the local domain RA that the pledge should
   connect to for the purposes of EST enrollment.

  +--------+             +--------+            +------+     +----------+
  | Pledge |             | EST RA |            | ACME |     | Cloud RA |
  +--------+             +--------+            +------+     |  / MASA  |
      |                                                     +----------+
      |                                                         |
           NOTE: Pre-Authorization of "domain.com" is complete
      |                                                         |
           STEP 1: Pledge requests Voucher from Cloud Registrar
      |                                                         |
      | POST /requestvoucher                                    |
      |-------------------------------------------------------->|
      |                                                         |
      | 200 OK Voucher (EST RA domain)                          |
      |<--------------------------------------------------------|
      |                      |                      |           |
           STEP 2: Pledge enrolls against local domain RA
      |                      |                      |           |



Friel, et al.            Expires April 26, 2020                 [Page 8]


Internet-Draft              ACME-INTEGRATIONS               October 2019


      | GET /csrattrs        |                      |           |
      |--------------------->|                      |           |
      |                      |                      |           |
      | 200 OK               |                      |           |
      | SEQUENCE {AttrOrOID} |                      |           |
      | SAN OID:             |                      |           |
      | "pledgeid.domain.com"|                      |           |
      |<---------------------|                      |           |
      |                      |                      |           |
      | POST /simpleenroll   |                      |           |
      | PCSK#10 CSR          |                      |           |
      | "pledgeid.domain.com"|                      |           |
      |--------------------->|                      |           |
      |                      |                      |           |
      | 202 Retry-After      |                      |           |
      |<---------------------|                      |           |
      |                      |                      |           |
           STEP 3: RA places ACME order
      |                      |                      |           |
      |                      | POST /newOrder       |           |
      |                      | "pledgeid.domain.com"|           |
      |                      |--------------------->|           |
      |                      |                      |           |
      |                      | 201 status=ready     |           |
      |                      |<---------------------|           |
      |                      |                      |           |
      |                      | POST /finalize       |           |
      |                      | PKCS#10 CSR          |           |
      |                      | "pledgeid.domain.com"|           |
      |                      |--------------------->|           |
      |                      |                      |           |
      |                      | 200 OK status=valid  |           |
      |                      |<---------------------|           |
      |                      |                      |           |
      |                      | POST /certificate    |           |
      |                      |--------------------->|           |
      |                      |                      |           |
      |                      | 200 OK               |           |
      |                      | PEM                  |           |
      |                      | "pledgeid.domain.com"|           |
      |                      |<---------------------|           |
      |                      |                      |           |
           STEP 4: Pledge retries enroll
      |                      |                      |           |
      | POST /simpleenroll   |                      |           |
      | PCSK#10 CSR          |                      |           |
      | "pledgeid.domain.com"|                      |           |
      |--------------------->|                      |           |



Friel, et al.            Expires April 26, 2020                 [Page 9]


Internet-Draft              ACME-INTEGRATIONS               October 2019


      |                      |                      |           |
      | 200 OK               |                      |           |
      | PKCS#7               |                      |           |
      | "pledgeid.domain.com"|                      |           |
      |<---------------------|                      |           |

6.  ACME Integration with TEAP

   TEAP [RFC7170] defines a tunnel-based EAP method that enables secure
   communication between a peer and a server by using TLS to establish a
   mutually authenticated tunnel.  TEAP enables certificate provisioning
   within the tunnel.  TEAP does not define how the TEAP server
   communicates with the CA.

   This section outlines how ACME could be used for communication
   between the TEAP server and the CA.  The example call flow leverages
   [I-D.friel-acme-subdomains] and shows the TEAP server proving
   ownership of a parent domain, with individual client certificates
   being subdomains under that parent domain.

   The example illustrates the TEAP server sending a Request-Action TLV
   including a CSR-Attributes TLV instructing the peer to send a CSR-
   Attributes TLV to the server.  This enables the server to indicate
   what fields the peer should include in the CSR that the peer sends in
   the PKCS#10 TLV.  For example, the TEAP server could instruct the
   peer what Subject or SAN entries to include in its CSR.

  +------+                +-------------+           +------+     +-----+
  | Peer |                | TEAP-Server |           | ACME |     | DNS |
  +------+                +-------------+           +------+     +-----+
      |                         |                      |           |
                 STEP 1: Pre-Authorization of parent domain
      |                         |                      |           |
      |                         | POST /newAuthz       |           |
      |                         |  "domain.com"        |           |
      |                         |--------------------->|           |
      |                         |                      |           |
      |                         | 201 authorizations   |           |
      |                         |<---------------------|           |
      |                         |                      |           |
      |                         | Publish DNS TXT      |           |
      |                         | "domain.com"         |           |
      |                         |--------------------------------->|
      |                         |                      |           |
      |                         | POST /challenge      |           |
      |                         |--------------------->|           |
      |                         |                      | Verify    |
      |                         |                      |---------->|



Friel, et al.            Expires April 26, 2020                [Page 10]


Internet-Draft              ACME-INTEGRATIONS               October 2019


      |                         | 200 status=valid     |           |
      |                         |<---------------------|           |
      |                         |                      |           |
      |                         | Delete DNS TXT       |           |
      |                         | "domain.com"         |           |
      |                         |--------------------------------->|
      |                         |                      |           |
      |                         |                      |           |
                 STEP 2: Establsh EAP Outer Tunnel
      |                         |                      |           |
      |  EAP-Request/           |                      |           |
      |   Type=Identity         |                      |           |
      |<------------------------|                      |           |
      |                         |                      |           |
      |  EAP-Response/          |                      |           |
      |   Type=Identity         |                      |           |
      |------------------------>|                      |           |
      |                         |                      |           |
      |  EAP-Request/           |                      |           |
      |   Type=TEAP,            |                      |           |
      |   TEAP Start,           |                      |           |
      |   Authority-ID TLV      |                      |           |
      |<------------------------|                      |           |
      |                         |                      |           |
      |  EAP-Response/          |                      |           |
      |   Type=TEAP,            |                      |           |
      |   TLS(ClientHello)      |                      |           |
      |------------------------>|                      |           |
      |                         |                      |           |
      |  EAP-Request/           |                      |           |
      |   Type=TEAP,            |                      |           |
      |   TLS(ServerHello,      |                      |           |
      |   Certificate,          |                      |           |
      |   ServerKeyExchange,    |                      |           |
      |   CertificateRequest,   |                      |           |
      |   ServerHelloDone)      |                      |           |
      |<------------------------|                      |           |
      |                         |                      |           |
      |  EAP-Response/          |                      |           |
      |   Type=TEAP,            |                      |           |
      |   TLS(Certificate,      |                      |           |
      |   ClientKeyExchange,    |                      |           |
      |   CertificateVerify,    |                      |           |
      |   ChangeCipherSpec,     |                      |           |
      |   Finished)             |                      |           |
      |------------------------>|                      |           |
      |                         |                      |           |
      |  EAP-Request/           |                      |           |



Friel, et al.            Expires April 26, 2020                [Page 11]


Internet-Draft              ACME-INTEGRATIONS               October 2019


      |   Type=TEAP,            |                      |           |
      |   TLS(ChangeCipherSpec, |                      |           |
      |   Finished),            |                      |           |
      |   {Crypto-Binding TLV,  |                      |           |
      |   Result TLV=Success}   |                      |           |
      |<------------------------|                      |           |
      |                         |                      |           |
      |  EAP-Response/          |                      |           |
      |   Type=TEAP,            |                      |           |
      |   {Crypto-Binding TLV,  |                      |           |
      |   Result TLV=Success}   |                      |           |
      |------------------------>|                      |           |
      |                         |                      |           |
      |  EAP-Request/           |                      |           |
      |   Type=TEAP,            |                      |           |
      |   {Request-Action TLV:  |                      |           |
      |     Status=Failure,     |                      |           |
      |     Action=Process-TLV, |                      |           |
      |     TLV=CSR-Attributes, |                      |           |
      |     TLV=PKCS#10}        |                      |           |
      |<------------------------|                      |           |
      |                         |                      |           |
                 STEP 3: Enroll for certificate
      |                         |                      |           |
      |  EAP-Response/          |                      |           |
      |   Type=TEAP,            |                      |           |
      |   {CSR-Attributes TLV}  |                      |           |
      |------------------------>|                      |           |
      |                         |                      |           |
      |  EAP-Request/           |                      |           |
      |   Type=TEAP,            |                      |           |
      |   {CSR-Attributes TLV}  |                      |           |
      |<------------------------|                      |           |
      |                         |                      |           |
      |  EAP-Response/          |                      |           |
      |   Type=TEAP,            |                      |           |
      |   {PKCS#10 TLV:         |                      |           |
      |   "pledgeid.domain.com"}|                      |           |
      |------------------------>|                      |           |
      |                         | POST /newOrder       |           |
      |                         | "pledgeid.domain.com"|           |
      |                         |--------------------->|           |
      |                         |                      |           |
      |                         | 201 status=ready     |           |
      |                         |<---------------------|           |
      |                         |                      |           |
      |                         | POST /finalize       |           |
      |                         | PKCS#10 CSR          |           |



Friel, et al.            Expires April 26, 2020                [Page 12]


Internet-Draft              ACME-INTEGRATIONS               October 2019


      |                         | "pledgeid.domain.com"|           |
      |                         |--------------------->|           |
      |                         |                      |           |
      |                         | 200 OK status=valid  |           |
      |                         |<---------------------|           |
      |                         |                      |           |
      |                         | POST /certificate    |           |
      |                         |--------------------->|           |
      |                         |                      |           |
      |                         | 200 OK               |           |
      |                         | PEM                  |           |
      |                         | "pledgeid.domain.com"|           |
      |                         |<---------------------|           |
      |                         |                      |           |
      |  EAP-Request/           |                      |           |
      |   Type=TEAP,            |                      |           |
      |   {PKCS#7 TLV,          |                      |           |
      |    Result TLV=Success}  |                      |           |
      |<------------------------|                      |           |
      |                         |                      |           |
      |  EAP-Response/          |                      |           |
      |   Type=TEAP,            |                      |           |
      |   {Result TLV=Success}  |                      |           |
      |------------------------>|                      |           |
      |                         |                      |           |
      |  EAP-Success            |                      |           |
      |<------------------------|                      |           |


7.  ACME Integration with TEAP-BRSKI

   TEAP-BRSKI [I-D.lear-eap-teap-brski] defines how to execute BRSKI at
   layer 2 inside a TEAP tunnel.  Similar to the TEAP proposal in the
   previous section, BRSKI-TEAP leverages the existing TEAP PKXS#10 and
   PKCS#7 mechanisms for certificate enrollment, and does not define how
   the TEAP server communicates with the CA.

   This section outlines how ACME could be used for communication
   between the TEAP server and the CA, and how this fits in with the
   TEAP-BRSKI proposal.

   Similar to baseline TEAP, the TEAP server can use the CSR-Atributes
   TLV to tell the peer what attributes to include in its CSR request.

   +--------+                +-------------+         +------+   +------+
   | Pledge |                | TEAP-Server |         | ACME |   | MASA |
   +--------+                +-------------+         +------+   +------+
       |                            |                     |           |



Friel, et al.            Expires April 26, 2020                [Page 13]


Internet-Draft              ACME-INTEGRATIONS               October 2019


                  NOTE: Pre-Authorization of "domain.com" is complete
                  and EAP outer tunnel is established as outlined in
                  the previous section
       |                            |                     |         |
                  STEP 1: Perform BRSKI Flow
       |                            |                     |         |
       | EAP-Request/               |                     |         |
       |  Type=TEAP,                |                     |         |
       |  {Request-Action TLV:      |                     |         |
       |    Status=Failure,         |                     |         |
       |    Action=Process-TLV,     |                     |         |
       |    TLV=Request-Voucher,    |                     |         |
       |    TLV=Trusted-Server-Root,|                     |         |
       |    TLV=CSR-Attributes,     |                     |         |
       |    TLV=PKCS#10}            |                     |         |
       |<---------------------------|                     |         |
       |                            |                     |         |
       | EAP-Response/              |                     |         |
       |  Type=TEAP,                |                     |         |
       |  {Request-Voucher TLV}     |                     |         |
       |--------------------------->| RequestVoucher      |         |
       |                            |-------------------/ | \------>|
       |                            |    Voucher          |         |
       |                            |<------------------/ | \-------|
       | EAP-Request/               |                     |         |
       |  Type=TEAP,                |                     |         |
       |  {Voucher TLV}             |                     |         |
       |<---------------------------|                     |         |
       |                            |                     |         |
                  STEP 2: Retrieve CA Configuration
       |                            |                     |         |
       | EAP-Response/              |                     |         |
       |  Type=TEAP,                |                     |         |
       |  {Trusted-Server-Root TLV} |                     |         |
       |--------------------------->|                     |         |
       |                            |                     |         |
       | EAP-Request/               |                     |         |
       |  Type=TEAP,                |                     |         |
       |  {Trusted-Server-Root TLV} |                     |         |
       |<---------------------------|                     |         |
       |                            |                     |         |
       | EAP-Response/              |                     |         |
       |  Type=TEAP,                |                     |         |
       |  {CSR-Attributes TLV}      |                     |         |
       |--------------------------->|                     |         |
       |                            |                     |         |
       | EAP-Request/               |                     |         |
       |  Type=TEAP,                |                     |         |



Friel, et al.            Expires April 26, 2020                [Page 14]


Internet-Draft              ACME-INTEGRATIONS               October 2019


       |  {CSR-Attributes TLV}      |                     |         |
       |<---------------------------|                     |         |
       |                            |                     |         |
                  STEP 3: Enroll for certificate
       |                            |                     |         |
       | EAP-Response/              |                     |         |
       |  Type=TEAP,                |                     |         |
       |   {PKCS#10 TLV:            |                     |         |
       |   "pledgeid.domain.com"}   |                     |         |
       |--------------------------->|                     |         |
       |                            |POST /newOrder       |         |
       |                            |"pledgeid.domain.com"|         |
       |                            |-------------------->|         |
       |                            |                     |         |
       |                            | 201 status=ready    |         |
       |                            |<--------------------|         |
       |                            |                     |         |
       |                            |POST /finalize       |         |
       |                            |PKCS#10 CSR          |         |
       |                            |"pledgeid.domain.com"|         |
       |                            |-------------------->|         |
       |                            |                     |         |
       |                            | 200 OK status=valid |         |
       |                            |<--------------------|         |
       |                            |                     |         |
       |                            | POST /certificate   |         |
       |                            |-------------------->|         |
       |                            |                     |         |
       |                            |200 OK               |         |
       |                            |PEM                  |         |
       |                            |"pledgeid.domain.com"|         |
       |                            |<--------------------|         |
       |                            |                     |         |
       | EAP-Request/               |                     |         |
       |  Type=TEAP,                |                     |         |
       |  {PKCS#7 TLV,              |                     |         |
       |   Result TLV=Success}      |                     |         |
       |<---------------------------|                     |         |
       |                            |                     |         |
       | EAP-Response/              |                     |         |
       |  Type=TEAP,                |                     |         |
       |  {Result TLV=Success}      |                     |         |
       |--------------------------->|                     |         |
       |                            |                     |         |
       | EAP-Success                |                     |         |
       |<---------------------------|                     |         |





Friel, et al.            Expires April 26, 2020                [Page 15]


Internet-Draft              ACME-INTEGRATIONS               October 2019


8.  IANA Considerations

   [todo]

9.  Security Considerations

   [todo]

10.  Informative References

   [I-D.friel-acme-subdomains]
              Friel, O., Barnes, R., and T. Hollebeek, "ACME for
              Subdomains", draft-friel-acme-subdomains-00 (work in
              progress), October 2019.

   [I-D.friel-anima-brski-cloud]
              Friel, O., Shekh-Yusef, R., and M. Richardson, "BRSKI
              Cloud Registrar", draft-friel-anima-brski-cloud-01 (work
              in progress), October 2019.

   [I-D.ietf-anima-bootstrapping-keyinfra]
              Pritikin, M., Richardson, M., Eckert, T., Behringer, M.,
              and K. Watsen, "Bootstrapping Remote Secure Key
              Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping-
              keyinfra-28 (work in progress), September 2019.

   [I-D.lear-eap-teap-brski]
              Lear, E., Friel, O., Cam-Winget, N., and D. Harkins,
              "Bootstrapping Key Infrastructure over EAP", draft-lear-
              eap-teap-brski-04 (work in progress), September 2019.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC7030]  Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
              "Enrollment over Secure Transport", RFC 7030,
              DOI 10.17487/RFC7030, October 2013,
              <https://www.rfc-editor.org/info/rfc7030>.

   [RFC7170]  Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna,
              "Tunnel Extensible Authentication Protocol (TEAP) Version
              1", RFC 7170, DOI 10.17487/RFC7170, May 2014,
              <https://www.rfc-editor.org/info/rfc7170>.






Friel, et al.            Expires April 26, 2020                [Page 16]


Internet-Draft              ACME-INTEGRATIONS               October 2019


   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8366]  Watsen, K., Richardson, M., Pritikin, M., and T. Eckert,
              "A Voucher Artifact for Bootstrapping Protocols",
              RFC 8366, DOI 10.17487/RFC8366, May 2018,
              <https://www.rfc-editor.org/info/rfc8366>.

   [RFC8555]  Barnes, R., Hoffman-Andrews, J., McCarney, D., and J.
              Kasten, "Automatic Certificate Management Environment
              (ACME)", RFC 8555, DOI 10.17487/RFC8555, March 2019,
              <https://www.rfc-editor.org/info/rfc8555>.

Appendix A.  Comments

Authors' Addresses

   Owen Friel
   Cisco

   Email: ofriel@cisco.com


   Richard Barnes
   Cisco

   Email: rlb@ipv.sx


   Rifaat Shekh-Yusef
   Avaya

   Email: rifaat.ietf@gmail.com

















Friel, et al.            Expires April 26, 2020                [Page 17]


Html markup produced by rfcmarkup 1.129d, available from https://tools.ietf.org/tools/rfcmarkup/