ACME Working Group R. Shoemaker
Internet-Draft ISRG
Intended status: Standards Track May 18, 2018
Expires: November 19, 2018

ACME IP Identifier Validation Extension


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

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Table of Contents

1. Introduction

The Automatic Certificate Management Environment (ACME) [I-D.ietf-acme-acme] 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 can be used to validate IP identifiers.

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, [RFC2119].

3. IP Identifier

[I-D.ietf-acme-acme] only defines the identifier type “dns” which is used to refer to fully qualified domain names. If a 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 [RFC4291] Section 2.2 for IPv6.

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” and “tls-sni-02” challenges from [I-D.ietf-acme-acme] Sections 8.3 and 8.4 respectively. 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. For the “http-01” challenge the Host header MUST be set to the IP address being used for validation per [RFC7230].

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

5. IANA Considerations

5.1. Identifier Types

Adds a new type to the Identifier list defined in Section 9.7.5 of [I-D.ietf-acme-acme] with the label “ip” and reference I-D.ietf-acme-ip.

5.2. Challenge Types

Add the value “ip” to the identifier type column for the “http-01” and “tls-sni-02” challenges.

6. Security Considerations

Given the often short delegation periods for IP addresses provided by various service providers CAs MAY want to impose shorter lifetimes for certificates which contain IP identifiers. They MAY also impose restrictions on IP identifiers which are in CIDRs known to be assigned to service providers who dynamically assign addresses to users for indeterminate periods of time.

7. 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.

8. Normative References

[FIPS180-4] Department of Commerce, National., "NIST FIPS 180-4, Secure Hash Standard", March 2012.
[I-D.ietf-acme-acme] Barnes, R., Hoffman-Andrews, J., McCarney, D. and J. Kasten, "Automatic Certificate Management Environment (ACME)", Internet-Draft draft-ietf-acme-acme-12, April 2018.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987.
[RFC1123] Braden, R., "Requirements for Internet Hosts - Application and Support", STD 3, RFC 1123, DOI 10.17487/RFC1123, October 1989.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.
[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.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, DOI 10.17487/RFC4291, February 2006.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006.
[RFC7230] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014.

Author's Address

Roland Bracewell Shoemaker Internet Security Research Group EMail: