draft-ietf-acme-ip-01.txt   draft-ietf-acme-ip-02.txt 
ACME Working Group R. Shoemaker ACME Working Group R. Shoemaker
Internet-Draft ISRG Internet-Draft ISRG
Intended status: Standards Track September 18, 2017 Intended status: Standards Track May 18, 2018
Expires: March 22, 2018 Expires: November 19, 2018
ACME IP Identifier Validation Extension ACME IP Identifier Validation Extension
draft-ietf-acme-ip-01 draft-ietf-acme-ip-02
Abstract Abstract
This document specifies identifiers and challenges required to enable This document specifies identifiers and challenges required to enable
the Automated Certificate Management Environment (ACME) to issue the Automated Certificate Management Environment (ACME) to issue
certificates for IP addresses. certificates for IP addresses.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. IP Identifier . . . . . . . . . . . . . . . . . . . . . . . . 2 3. IP Identifier . . . . . . . . . . . . . . . . . . . . . . . . 2
4. Identifier Validation Challenges . . . . . . . . . . . . . . 3 4. Identifier Validation Challenges . . . . . . . . . . . . . . 3
4.1. Reverse DNS . . . . . . . . . . . . . . . . . . . . . . . 3 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
4.2. Existing Challenges . . . . . . . . . . . . . . . . . . . 5 5.1. Identifier Types . . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5.2. Challenge Types . . . . . . . . . . . . . . . . . . . . . 3
5.1. Identifier Types . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 3
5.2. Challenge Types . . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 3
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 8. Normative References . . . . . . . . . . . . . . . . . . . . 3
6.1. Certificate Lifetime . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
8. Normative References . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
The Automatic Certificate Management Environment (ACME) The Automatic Certificate Management Environment (ACME)
[I-D.ietf-acme-acme] only defines challenges for validating control [I-D.ietf-acme-acme] only defines challenges for validating control
of DNS host name identifiers which limits its use to being used for of DNS host name identifiers which limits its use to being used for
issuing certificates for these identifiers. In order to allow issuing certificates for DNS identifiers. In order to allow
validation of IPv4 and IPv6 identifiers for inclusion in X.509 validation of IPv4 and IPv6 identifiers for inclusion in X.509
certificates this document defines a new challenge type and specifies certificates this document specifies how challenges defined in the
how challenges defined in the original ACME specification can be used original ACME specification can be used to validate IP identifiers.
to validate IP identifiers.
2. Terminology 2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED", In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119 and "OPTIONAL" are to be interpreted as described in BCP 14,
[RFC2119]. [RFC2119].
3. IP Identifier 3. IP Identifier
ACME only defines the identifier type "dns" which is used to refer to [I-D.ietf-acme-acme] only defines the identifier type "dns" which is
fully qualified domain names. If a ACME server wishes to request used to refer to fully qualified domain names. If a ACME server
proof that a user controls a IPv4 or IPv6 address it MUST create an wishes to request proof that a user controls a IPv4 or IPv6 address
authorization with the identifier type "ip". The value field of the it MUST create an authorization with the identifier type "ip". The
identifier MUST contain the textual form of the address as defined in value field of the identifier MUST contain the textual form of the
RFC 1123 [RFC1123] Section 2.1 for IPv4 and in RFC 4291 [RFC4291] address as defined in [RFC1123] Section 2.1 for IPv4 and in [RFC4291]
Section 2.2 for IPv6. Section 2.2 for IPv6.
An identifier for the IPv6 address 2001:db8::1 would be formatted An identifier for the IPv6 address 2001:db8::1 would be formatted
like so: like so:
{"type": "ip", "value": "2001:db8::1"} {"type": "ip", "value": "2001:db8::1"}
4. Identifier Validation Challenges 4. Identifier Validation Challenges
When creating an authorization for a identifier with the type "ip"
the following challenge types MAY be used to perform validation.
4.1. Reverse DNS
With Reverse DNS validation the client proves control of an IP
address by provisioning a TXT resource record containing a designated
value for a specific validation domain name constructed using the
value of the PTR record for the reverse mapping of the address.
type (required, string): The string "reverse-dns-01".
token (required, string): A random value that uniquely identifies
the challenge. This value MUST have at least 128 bits of entropy,
in order to prevent an attacker from guessing it. It MUST NOT
contain any characters outside the base64url [RFC4648] alphabet,
including padding characters ("=").
GET /acme/authz/1234/2 HTTP/1.1
Host: example.com
HTTP/1.1 200 OK
{
"type": "reverse-dns-01",
"url": "https://example.com/acme/authz/1234/2",
"status": "pending",
"token": "evaGxfADs6pSRb2LAv9IZf17Dt3juxGJ-PCt92wr-oA"
}
A client responds to this challenge by constructing a key
authorization from the "token" value provided in the challenge and
the client's ACME account key. The client then computes the SHA-256
digest [FIPS180-4] of the key authorization. The record provisioned
to the authoritative DNS server is the base64url encoding of this
digest.
The client constructs the validation domain name by prepending the
label "_acme-challenge" to the domain name referenced in the PTR
resource record for the IN-ADDR.ARPA [RFC1034] or IP6.ARPA [RFC3596]
reverse mapping of the IP address. The client then provisions a TXT
record with the digest for this name.
For example, if the IP address being validated is 2001:db8::1 and its
IP6.ARPA mapping had the following PTR record:
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. 300 IN PTR example.com
then the client would provision the following DNS record:
_acme-challenge.example.com. 300 IN TXT "gfj9Xq...Rg85nM"
The response to the Reverse DNS challenge provides the computed key
authorization to acknowledge that the client is ready to fulfill this
challenge.
keyAuthorization (required, string): The key authorization for this
challenge.
POST /acme/authz/1234/2
Host: example.com
Content-Type: application/jose+json
{
"protected": base64url({
"alg": "ES256",
"kid": "https://example.com/acme/acct/1",
"nonce": "JHb54aT_KTXBWQOzGYkt9A",
"url": "https://example.com/acme/authz/1234/2"
}),
"payload": base64url({
"keyAuthorization": "evaGxfADs...62jcerQ"
}),
"signature": "Q1bURgJoEslbD1c5...3pYdSMLio57mQNN4"
}
On receiving a response, the server MUST verify that the key
authorization in the response matches the "token" value in the
challenge and the client's ACME account key. If they do not match,
then the server MUST return an HTTP error in response to the POST
request in which the client sent the challenge.
To validate a DNS challenge, the server performs the following steps:
1. Compute the SHA-256 digest of the key authorization
2. Query for a PTR record for the IP identifier's relevant reverse
mapping based on its version
3. Query for TXT records for the computed validation domain name
4. Verify that the contents of one of the TXT records matches the
digest value
If all of the above verifications succeed, then the validation is
successful. If no PTR or TXT DNS records are found, or the returned
TXT records do not contain the expected key authorization digest,
then the validation fails.
4.2. Existing Challenges
IP identifiers MAY be used with the existing "http-01" and "tls-sni- IP identifiers MAY be used with the existing "http-01" and "tls-sni-
02" challenges from draft-ietf-acme-acme Sections 8.3 and 8.4 02" challenges from [I-D.ietf-acme-acme] Sections 8.3 and 8.4
respectively. To use IP identifiers with these challenges their respectively. To use IP identifiers with these challenges their
initial DNS resolution step MUST be skipped and the address used for initial DNS resolution step MUST be skipped and the IP address used
validation MUST be the value of the identifier. For the "http-01" for validation MUST be the value of the identifier. For the "http-
challenge the Host header should be set to the IP address being used 01" challenge the Host header MUST be set to the IP address being
for validation per RFC 7230. used for validation per [RFC7230].
The existing "dns-01" challenge MUST NOT be used to validate IP The existing "dns-01" challenge MUST NOT be used to validate IP
identifiers. identifiers.
5. IANA Considerations 5. IANA Considerations
5.1. Identifier Types 5.1. Identifier Types
Adds a new type to the Identifier list defined in Section 9.7.5 of Adds a new type to the Identifier list defined in Section 9.7.5 of
draft-ietf-acme-acme with the label "ip" and reference draft-ietf- [I-D.ietf-acme-acme] with the label "ip" and reference I-D.ietf-acme-
acme-ip. ip.
5.2. Challenge Types 5.2. Challenge Types
Adds a new type to the Challenge list defined in Section 9.7.6 of
draft-ietf-acme-acme with the label "reverse-dns-01", identifier type
"ip", and reference draft-ietf-acme-ip.
Add the value "ip" to the identifier type column for the "http-01" Add the value "ip" to the identifier type column for the "http-01"
and "tls-sni-02" challenges. and "tls-sni-02" challenges.
6. Security Considerations 6. Security Considerations
6.1. Certificate Lifetime
Given the often short delegation periods for IP addresses provided by Given the often short delegation periods for IP addresses provided by
various service providers CAs MAY want to impose shorter lifetimes various service providers CAs MAY want to impose shorter lifetimes
for certificates which contain IP identifiers. They MAY also impose for certificates which contain IP identifiers. They MAY also impose
restrictions on IP identifiers which are in CIDRs known to be restrictions on IP identifiers which are in CIDRs known to be
assigned to service providers who dynamically assign addresses to assigned to service providers who dynamically assign addresses to
users for indeterminate periods of time. users for indeterminate periods of time.
7. Acknowledgments 7. Acknowledgments
The author would like to thank those who contributed to this document The author would like to thank those who contributed to this document
and offered editorial advice, especially: Jacob Hoffman-Andrews and and offered editorial and technical input, especially Jacob Hoffman-
Daniel McCarney. Andrews and Daniel McCarney.
8. Normative References 8. Normative References
[FIPS180-4] [FIPS180-4]
Department of Commerce, National., "NIST FIPS 180-4, Department of Commerce, National., "NIST FIPS 180-4,
Secure Hash Standard", March 2012, Secure Hash Standard", March 2012,
<http://csrc.nist.gov/publications/fips/fips180-4/ <http://csrc.nist.gov/publications/fips/fips180-4/
fips-180-4.pdf>. fips-180-4.pdf>.
[I-D.ietf-acme-acme] [I-D.ietf-acme-acme]
Barnes, R., Hoffman-Andrews, J., and J. Kasten, "Automatic Barnes, R., Hoffman-Andrews, J., McCarney, D., and J.
Certificate Management Environment (ACME)", draft-ietf- Kasten, "Automatic Certificate Management Environment
acme-acme-07 (work in progress), June 2017. (ACME)", draft-ietf-acme-acme-12 (work in progress), April
2018.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<https://www.rfc-editor.org/info/rfc1034>. <https://www.rfc-editor.org/info/rfc1034>.
[RFC1123] Braden, R., Ed., "Requirements for Internet Hosts - [RFC1123] Braden, R., Ed., "Requirements for Internet Hosts -
Application and Support", STD 3, RFC 1123, Application and Support", STD 3, RFC 1123,
DOI 10.17487/RFC1123, October 1989, <https://www.rfc- DOI 10.17487/RFC1123, October 1989,
editor.org/info/rfc1123>. <https://www.rfc-editor.org/info/rfc1123>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, <https://www.rfc- DOI 10.17487/RFC2119, March 1997,
editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi, [RFC3596] Thomson, S., Huitema, C., Ksinant, V., and M. Souissi,
"DNS Extensions to Support IP Version 6", STD 88, "DNS Extensions to Support IP Version 6", STD 88,
RFC 3596, DOI 10.17487/RFC3596, October 2003, RFC 3596, DOI 10.17487/RFC3596, October 2003,
<https://www.rfc-editor.org/info/rfc3596>. <https://www.rfc-editor.org/info/rfc3596>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>. 2006, <https://www.rfc-editor.org/info/rfc4291>.
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