



ACME Working Group                                          R. Shoemaker
Internet-Draft                                                      ISRG
Intended status: Standards Track                        October 01, 2019
Expires: April 3, 2020


                ACME IP Identifier Validation Extension
                         draft-ietf-acme-ip-08

Abstract

   This document specifies identifiers and challenges required to enable
   the Automated Certificate Management Environment (ACME) to issue
   certificates for IP addresses.

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 3, 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
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.





Shoemaker                 Expires April 3, 2020                 [Page 1]

Internet-Draft                   ACME-IP                    October 2019


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  IP Identifier . . . . . . . . . . . . . . . . . . . . . . . .   2
   4.  Identifier Validation Challenges  . . . . . . . . . . . . . .   3
   5.  HTTP Challenge  . . . . . . . . . . . . . . . . . . . . . . .   3
   6.  TLS with Application Level Protocol Negotiation (TLS ALPN)
       Challenge . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   7.  DNS Challenge . . . . . . . . . . . . . . . . . . . . . . . .   3
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
     8.1.  Identifier Types  . . . . . . . . . . . . . . . . . . . .   3
     8.2.  Challenge Types . . . . . . . . . . . . . . . . . . . . .   4
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
     9.1.  CA Policy Considerations  . . . . . . . . . . . . . . . .   4
   10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   4
   11. Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   The Automatic Certificate Management Environment (ACME) [RFC8555]
   only defines challenges for validating control of DNS host name
   identifiers, which limits its use to being used for issuing
   certificates for DNS identifiers.  In order to allow validation of
   IPv4 and IPv6 identifiers for inclusion in X.509 certificates, this
   document specifies how challenges defined in the original ACME
   specification and the TLS-ALPN extension specification
   [I-D.ietf-acme-tls-alpn] can be used to validate IP identifiers.

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.

3.  IP Identifier

   [RFC8555] only defines the identifier type "dns", which is used to
   refer to fully qualified domain names.  If an ACME server wishes to
   request proof that a user controls a IPv4 or IPv6 address, it MUST
   create an authorization with the identifier type "ip".  The value
   field of the identifier MUST contain the textual form of the address
   as defined in [RFC1123] Section 2.1 for IPv4 and in [RFC5952]
   Section 4 for IPv6.




Shoemaker                 Expires April 3, 2020                 [Page 2]

Internet-Draft                   ACME-IP                    October 2019


   An identifier for the IPv6 address 2001:db8::1 would be formatted
   like so:

   {"type": "ip", "value": "2001:db8::1"}

4.  Identifier Validation Challenges

   IP identifiers MAY be used with the existing "http-01" (see
   Section 8.3 of [RFC8555]) and "tls-alpn-01" (see Section 3 of
   [I-D.ietf-acme-tls-alpn]).  To use IP identifiers with these
   challenges, their initial DNS resolution step MUST be skipped, and
   the IP address used for validation MUST be the value of the
   identifier.

5.  HTTP Challenge

   For the "http-01" challenge, the Host header field MUST be set to the
   IP address being used for validation per [RFC7230].  The textual form
   of this address MUST be as defined in [RFC1123] Section 2.1 for IPv4
   and in [RFC5952] Section 4 for IPv6.

6.  TLS with Application Level Protocol Negotiation (TLS ALPN) Challenge

   For the "tls-alpn-01" challenge, the subjectAltName extension in the
   validation certificate MUST contain a single iPAddress that matches
   the address being validated.  As [RFC6066] does not permit IP
   addresses to be used in the SNI extension HostName field, the server
   MUST instead use the IN-ADDR.ARPA [RFC1034] or IP6.ARPA [RFC3596]
   reverse mapping of the IP address as the HostName field value instead
   of the IP address string representation itself.  For example, if the
   IP address being validated is 2001:db8::1, the SNI HostName field
   should contain "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d
   .0.1.0.0.2.ip6.arpa".

7.  DNS Challenge

   The existing "dns-01" challenge MUST NOT be used to validate IP
   identifiers.

8.  IANA Considerations

8.1.  Identifier Types

   Adds a new type to the "ACME Identifier Types" registry defined in
   Section 9.7.7 of [RFC8555] with Label "ip" and Reference "I-D.ietf-
   acme-ip".





Shoemaker                 Expires April 3, 2020                 [Page 3]

Internet-Draft                   ACME-IP                    October 2019


8.2.  Challenge Types

   Adds two new entries to the "ACME Validation Methods" registry
   defined in Section 9.7.8 of [RFC8555].  These entries are defined
   below:

        +-------------+-----------------+------+------------------+
        | Label       | Identifier Type | ACME | Reference        |
        +-------------+-----------------+------+------------------+
        | http-01     | ip              | Y    | I-D.ietf-acme-ip |
        |             |                 |      |                  |
        | tls-alpn-01 | ip              | Y    | I-D.ietf-acme-ip |
        +-------------+-----------------+------+------------------+

9.  Security Considerations

   The extensions to ACME described in this document do not deviate from
   the broader threat model described in [RFC8555] Section 10.1.

9.1.  CA Policy Considerations

   This document only specifies how a ACME server may validate that a
   certificate applicant controls a IP identifier at the time of
   validation.  The CA may wish to perform additional checks not
   specified in this document.  For example, if the CA believes an IP
   identifier belongs to a ISP or cloud service provider with short
   delegation periods, they may wish to impose additional restrictions
   on certificates requested for that identifier.

10.  Acknowledgments

   The author would like to thank those who contributed to this document
   and offered editorial and technical input, especially Jacob Hoffman-
   Andrews and Daniel McCarney.

11.  Normative References

   [I-D.ietf-acme-tls-alpn]
              Shoemaker, R., "ACME TLS ALPN Challenge Extension", draft-
              ietf-acme-tls-alpn-06 (work in progress), September 2019.

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
              <https://www.rfc-editor.org/info/rfc1034>.







Shoemaker                 Expires April 3, 2020                 [Page 4]

Internet-Draft                   ACME-IP                    October 2019


   [RFC1123]  Braden, R., Ed., "Requirements for Internet Hosts -
              Application and Support", STD 3, RFC 1123,
              DOI 10.17487/RFC1123, October 1989,
              <https://www.rfc-editor.org/info/rfc1123>.

   [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>.

   [RFC3596]  Thomson, S., Huitema, C., Ksinant, V., and M. Souissi,
              "DNS Extensions to Support IP Version 6", STD 88,
              RFC 3596, DOI 10.17487/RFC3596, October 2003,
              <https://www.rfc-editor.org/info/rfc3596>.

   [RFC5952]  Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
              Address Text Representation", RFC 5952,
              DOI 10.17487/RFC5952, August 2010,
              <https://www.rfc-editor.org/info/rfc5952>.

   [RFC6066]  Eastlake 3rd, D., "Transport Layer Security (TLS)
              Extensions: Extension Definitions", RFC 6066,
              DOI 10.17487/RFC6066, January 2011,
              <https://www.rfc-editor.org/info/rfc6066>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,
              <https://www.rfc-editor.org/info/rfc7230>.

   [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>.

   [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>.

Author's Address

   Roland Bracewell Shoemaker
   Internet Security Research Group

   Email: roland@letsencrypt.org






Shoemaker                 Expires April 3, 2020                 [Page 5]
