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]
