Internet Engineering Task Force (IETF) O. Gudmundsson
Request for Comments: 7218 Shinkuro Inc.
Updates: 6698 April 2014
Category: Standards Track
ISSN: 2070-1721
Adding Acronyms to Simplify Conversations about
DNS-Based Authentication of Named Entities (DANE)
Abstract
Experience has shown that people get confused when discussing the
three numeric fields of the TLSA record. This document specifies
descriptive acronyms for the three numeric fields in TLSA records.
This document updates the format of the IANA registry created by RFC
6698.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/RFC 7218.
Copyright Notice
Copyright (c) 2014 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
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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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.
Gudmundsson Standards Track [Page 1]
RFC 7218 Adding Acronyms to DANE Registries April 2014
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 2
2.1. TLSA Certificate Usages Registry . . . . . . . . . . . . 3
2.2. TLSA Selectors . . . . . . . . . . . . . . . . . . . . . 3
2.3. TLSA Matching Types . . . . . . . . . . . . . . . . . . . 4
3. Examples of Usage . . . . . . . . . . . . . . . . . . . . . . 4
3.1. TLSA Records Using/Displaying the Acronyms . . . . . . . 4
3.2. Acronym Use in a Specification Example . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 4
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 5
1. Introduction
During discussions on how to add DNS-Based Authentication of Named
Entities (DANE) [RFC 6698] technology to new protocols and services,
people were repeatedly confused as to what the numeric values stood
for and even the order of the fields of a TLSA record (note that TLSA
is not an acronym but a name). This document updates the IANA
registry definition for the TLSA record to add a column containing an
acronym for each specified field, in order to reduce confusion. This
document does not change the DANE protocol in any way.
It is expected that DANE parsers in applications and DNS software can
adopt parsing the acronyms for each field.
2. IANA Considerations
This document applies to the "DNS-Based Authentication of Named
Entities (DANE) Parameters" registry located at <http://www.iana.org/
assignments/dane-parameters>. IANA has added a column with an
acronym to each of the sub-registries.
[RFC 6698] and this document are the referenced documents for the
three sub-registries.
As these acronyms are offered for human consumption, case does not
matter; it is expected that software that parses TLSA records will
handle upper-, mixed-, or lower-case characters as input.
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RFC 7218 Adding Acronyms to DANE Registries April 2014
2.1. TLSA Certificate Usages Registry
The reference for this registry has been updated to include both
[RFC 6698] and this document.
+-------+----------+--------------------------------+-------------+
| Value | Acronym | Short Description | Reference |
+-------+----------+--------------------------------+-------------+
| 0 | PKIX-TA | CA constraint | [RFC 6698] |
| 1 | PKIX-EE | Service certificate constraint | [RFC 6698] |
| 2 | DANE-TA | Trust anchor assertion | [RFC 6698] |
| 3 | DANE-EE | Domain-issued certificate | [RFC 6698] |
| 4-254 | | Unassigned | |
| 255 | PrivCert | Reserved for Private Use | [RFC 6698] |
+-------+----------+--------------------------------+-------------+
Table 1: TLSA Certificate Usages
2.2. TLSA Selectors
The reference for this registry has been updated to include both
[RFC 6698] and this document.
+-------+---------+--------------------------+-------------+
| Value | Acronym | Short Description | Reference |
+-------+---------+--------------------------+-------------+
| 0 | Cert | Full certificate | [RFC 6698] |
| 1 | SPKI | SubjectPublicKeyInfo | [RFC 6698] |
| 2-254 | | Unassigned | |
| 255 | PrivSel | Reserved for Private Use | [RFC 6698] |
+-------+---------+--------------------------+-------------+
Table 2: TLSA Selectors
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RFC 7218 Adding Acronyms to DANE Registries April 2014
2.3. TLSA Matching Types
The reference for this registry has been updated to include both
[RFC 6698] and this document.
+-------+-----------+--------------------------+-------------+
| Value | Acronym | Short Description | Reference |
+-------+-----------+--------------------------+-------------+
| 0 | Full | No hash used | [RFC 6698] |
| 1 | SHA2-256 | 256 bit hash by SHA2 | [RFC 6234] |
| 2 | SHA2-512 | 512 bit hash by SHA2 | [RFC 6234] |
| 3-254 | | Unassigned | |
| 255 | PrivMatch | Reserved for Private Use | [RFC 6698] |
+-------+-----------+--------------------------+-------------+
Table 3: TLSA Matching Types
3. Examples of Usage
Two examples are described below.
3.1. TLSA Records Using/Displaying the Acronyms
_666._tcp.first.example. TLSA PKIX-TA CERT SHA2-512 {blob}
_666._tcp.second.example. TLSA DANE-TA SPKI SHA2-256 {blob}
3.2. Acronym Use in a Specification Example
Protocol FOO only allows TLSA records using PKIX-EE and DANE-EE, with
selector SPKI, and using SHA2-512.
4. Security Considerations
This document only changes registry fields and does not change the
behavior of any protocol. The hope is to reduce confusion, which
would lead to better specification and operations.
5. Acknowledgements
Scott Schmit offered really good suggestions to decrease the
possibility of confusion. Viktor Dukhovni provided comments from the
expert point of view. Jim Schaad, Wes Hardaker, and Paul Hoffman
provided feedback during WGLC. Dan Romascanu and Tobias Gondrom
pointed out a few defects during the IESG last call.
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RFC 7218 Adding Acronyms to DANE Registries April 2014
6. References
6.1. Normative References
[RFC 6698] Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
of Named Entities (DANE) Transport Layer Security (TLS)
Protocol: TLSA", RFC 6698, August 2012.
6.2. Informative References
[RFC 6234] Eastlake, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234, May 2011.
Author's Address
Olafur Gudmundsson
Shinkuro Inc.
4922 Fairmont Av, Suite 250
Bethesda, MD 20814
USA
EMail: ogud@ogud.com
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