Certification Authority Authorization (CAA) Validation for IP Addresses
draft-shoemaker-caa-ip-00

Network Working Group                                       R. Shoemaker
Internet-Draft                                                      ISRG
Intended status: Standards Track                      September 11, 2017
Expires: March 15, 2018

Certification Authority Authorization (CAA) Validation for IP Addresses
                       draft-shoemaker-caa-ip-00

Abstract

   The Certification Authority Authorization (CAA) RFC specifies a
   method for users to restrict which Certificate Authorities (CAs) are
   authorized to issue certificates for their DNS domain names.  This
   document extends that specification to provide a method for holders
   of IP addresses to do the same.

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 March 15, 2018.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Certification Authority Restriction Properties  . . . . .   3
   5.  Normative References  . . . . . . . . . . . . . . . . . . . .   3
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   This document describes an extension to RFC 6844 [RFC6844] which
   allows for the use of Certification Authority Authorization DNS
   Records to be used to restrict issuance of certificates to IP
   addresses instead of just DNS names.  This is done by defining a new
   lookup mechanism for IPv4 and IPv6 addresses as previously a
   mechanism only existed for DNS names.

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-Wildcard
   implementations.

3.  Mechanism

   Before issuing a certificate containing a IP address a compliant CA
   MUST check for the relevant CAA Resource Record set.  If such a
   record set exists a CA MUST NOT issue a certificate unless the
   records in the set are consistent with the request and the policies
   of the CA.

   A certificate request MAY specify more than one IP address in which
   case CAs MUST verify the CA Resource Record set for all the IP
   addresses specified in the request.

   As defined in RFC 2818 [RFC2818] IP addresses in certificates must
   match exactly with the requested URI so CAs MUST NOT consider CAA
   records with the "issuewild" tag to be part of the relevant Resource
   Record set for a IP address.

   Unlike the mechanism defined in RFC 6844 [RFC6844] this mechanism
   doesn't involve climbing the DNS tree and only requires querying a
   single DNS name.  The relevant Resource Record set for a given IP

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   address is found by querying the reverse mapping zone for the IP for
   CAA records.

   Given a certificate request containing the IPv6 address "2001:db8::1"
   the relevant query for the reverse mapping within the IP6.ARPA
   [RFC3596] zone would be:

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. IN CAA

   And for a request containing the IPv4 address "192.0.2.1" the
   relevant query for the reverse mapping within the IN-ADDR.ARPA
   [RFC1034] zone would be:

   1.2.0.192.in-addr.arpa. IN CAA

   When doing queries CAs SHOULD either use a resolver that chases CNAME
   records or manually chase CNAMEs themselves in order to allow for
   zone delegations [RFC2317].

4.  IANA Considerations

4.1.  Certification Authority Restriction Properties

   Change the contents of the Meaning column for the "issue" Tag to say
   "Authorization Entry by Domain or IP address" and add "draft-
   shoemaker-caa-ip" to the References column.

5.  Normative References

   [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>.

   [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>.

   [RFC2317]  Eidnes, H., de Groot, G., and P. Vixie, "Classless IN-
              ADDR.ARPA delegation", BCP 20, RFC 2317,
              DOI 10.17487/RFC2317, March 1998, <https://www.rfc-
              editor.org/info/rfc2317>.

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818,
              DOI 10.17487/RFC2818, May 2000, <https://www.rfc-
              editor.org/info/rfc2818>.

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   [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>.

   [RFC6844]  Hallam-Baker, P. and R. Stradling, "DNS Certification
              Authority Authorization (CAA) Resource Record", RFC 6844,
              DOI 10.17487/RFC6844, January 2013, <https://www.rfc-
              editor.org/info/rfc6844>.

Author's Address

   Roland Bracewell Shoemaker
   ISRG

   Email: roland@letsencrypt.org

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