D/TLS IANA Registry Updates
draft-ietf-tls-iana-registry-updates-01

Abstract

This document changes the IANA registry policy for a number of registries related to DTLS and TLS, renames some of the registries for consistency, and adds notes to many of the registries. As a result, this document updates many RFCs (see updates header).

Status of This Memo

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This Internet-Draft will expire on October 30, 2017.

Copyright Notice

Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

• 1. Process Note
• 2. Introduction
• 3. Add “TLS” to Registry Names
• 4. Aligning with RFC 5226
• 5. Session Ticket TLS Extension
• 6. TLS ExtensionType Values
• 7. TLS Cipher Suite Registry
• 8. TLS Supported Groups
• 9. TLS ClientCertificateType Identifiers
• 10. New Session Ticket TLS Handshake Message Type
• 11. TLS Exporter Label Registry
• 12. Add Missing Item to TLS Alert Registry
• 13. TLS Certificate Types
• 14. Orphaned Extensions
• 15. Orphaned Registries
• 16. Designated Expert Pool
• 17. Security Considerations
• 18. IANA Considerations
• 19. References
• 19.1. Normative References
• 19.2. Informative References
• Authors' Addresses

1. Process Note

As the authors of this draft are also the WG chairs, the responsible Area Director has agreed to judge consensus.

RFC EDITOR: Please delete section prior to publication.

2. Introduction

This document requests that IANA make changes to a number of DTLS- and TLS-related IANA registries.

In this document, we use the term “(D)TLS” to refer to registries that apply to both TLS and DTLS.

• Add “TLS” to registries’ names for consistency amongst TLS-related registries.
• Change the IANA registry policy [RFC5226] for the TLS ExtensionType Values, TLS Cipher Suite, and TLS ClientCertificateType Identifiers registries. These changes register a small part of these code spaces for experimentation and private use.
• Add designated expert instructions as notes in the TLS ExtensionType Values, TLS Cipher Suite, TLS ClientCertificateType Identifiers, and TLS Exporter Label registries to inform users about what to expect from the designated expert.
• Add notes to indicate whether an extension, certain values of an extension, or an entire registry is only applicable pre-(D)TLS 1.3.
• Rename the NewSessionTicket TLS HandshakeType message registry entry [RFC5077] to new_session_ticket to match the naming nomenclature for the other Handshake type names and to match with existing implementations.
• Rename the SessionTicket TLS extension to session_ticket to match the nomenclature for the other extensions’ names.
• Add missing entry to the TLS Alert Registry for the no_application_protocol alert defined in [RFC7301].
• Added “Recommended” column to TLS ExtensionType Values, TLS Cipher Suite, TLS Certificate Types, TLS Supported Groups, and TLS Exporters Label registries. Initial values marked “Yes” are specified in IETF Standards Track documents; all others are marked “No”. This new column is intended to alter the incorrect perception that getting a code point somehow legitimizes the extension, cipher suite/algorithm, or exporter.
• Establish Designated Expert pool rules for Specification Required registries.

This document proposes no changes to the registration policies for TLS Alert [I-D.ietf-tls-tls13], TLS ContentType [I-D.ietf-tls-tls13], TLS HandshakeType, [I-D.ietf-tls-tls13] and TLS Certificate Status Types [RFC6961]; the existing policies (Standards Action for the first three; IETF Review for the last), are appropriate for these one-byte code points because of their scarcity.

3. Add “TLS” to Registry Names

IANA is to update the names of the following registries to add “TLS” to for consistency with the other TLS-related extensions:

• Application-Layer Protocol Negotiation (ALPN) Protocol IDs,
• ExtensionType Values,
• Heartbeat Message Types,
• Heartbeat Modes, and
• Supported Groups.

IANA is also to add a reference to this document for the registry whose names have been updated as a result of the above change. The remainder of this document will use the registry names with the “TLS” prefix.

4. Aligning with RFC 5226

Many of the TLS-related IANA registries were defined prior to [RFC5226] where “IETF Consensus” was used instead of the RFC5226-defined “IETF Review”. To align with the new terminology, IANA is to update to use “IETF Review” in place of “IETF Consensus” in the following registries:

• TLS Authorization Data Formats
• TLS Supplemental Data Formats (SupplementalDataType)

This is not a universal change as some registries originally defined with “IETF Consensus” are undergoing other changes either as a result of this document or [I-D.ietf-tls-rfc4492bis].

5. Session Ticket TLS Extension

The nomenclature for the registry entries in the TLS ExtensionType Values registry correspond to the presentation language field name except for entry 35. To ensure that the values in the registry are consistently identified in the registry, IANA is to rename entry 35 to “session_ticket (renamed from “SessionTicket TLS”)”.

6. TLS ExtensionType Values

IANA is to update the TLS ExtensionType Values registry as follows:

• Change the registry policy to:
  
  Values with the first byte in the range 0-254 (decimal) are assigned via Specification Required [RFC5226]. Values with the first byte 255 (decimal) are reserved for Private Use [RFC5226].
• Update the “References” to also refer to this document.
• Add the following note:
  
  Note: Experts are to verify that there is in fact a publicly available standard.
• Add a “Recommended” column with the contents as listed below. This table has been generated by marking Standards Track RFCs as “Yes” and all others as “No”. Future extensions MUST define the value of this column. A Standards Track document [RFC5226] is required to register an extension with the value “Yes”.

7. TLS Cipher Suite Registry

IANA is to update the TLS Cipher Suite registry as follows:

• Change the registry policy to:
  
  Values with the first byte in the range 0-254 (decimal) are assigned via Specification Required [RFC5226]. Values with the first byte 255 (decimal) are reserved for Private Use [RFC2434].
• Add a “Recommended” column to the cipher suite registry. The cipher suites that follow in the two tables are marked as “Yes”. All other cipher suites are marked as “No”. Future cipher suites MUST define the value of the Recommended column. A Standards Track document [RFC5226] is required to register a cipher suite with the value “Yes”.
• Update the reference for this registry to also point to this document.

The cipher suites that follow are standards track server-authenticated (and optionally client-authenticated) cipher suites which are currently available in TLS 1.2. The notable exception are the ECDHE AES GCM cipher suites which are not yet standards track prior to the publication of this specification, but this document promotes those 4 cipher suites to standards track (see TO-DO insert reference).

RFC EDITOR: Please delete the sentence beginning with “The notable exception …” after RFC 5289 has been promoted to Proposed Standard.

Cipher Suite Name                             | Value
----------------------------------------------+------------
TLS_DHE_RSA_WITH_AES_128_GCM_SHA256           | {0x00,0x9E}
TLS_DHE_RSA_WITH_AES_256_GCM_SHA384           | {0x00,0x9F}
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256       | {0xC0,0x2B}
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384       | {0xC0,0x2C}
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256         | {0xC0,0x2F}
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384         | {0xC0,0x30}
TLS_DHE_RSA_WITH_AES_128_CCM                  | {0xC0,0x9E}
TLS_DHE_RSA_WITH_AES_256_CCM                  | {0xC0,0x9F}
TLS_DHE_RSA_WITH_AES_128_CCM_8                | {0xC0,0xA2}
TLS_DHE_RSA_WITH_AES_256_CCM_8                | {0xC0,0xA3}
TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256   | {0xCC,0xA8}
TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 | {0xCC,0xA9}
TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256     | {0xCC,0xAA}

The cipher suites that follow are standards track ephemeral pre-shared key cipher suites which are available in TLS 1.2. [RFC6655] is inconsistent with respect to the ordering of components within PSK AES CCM cipher suite names; those names are used here without modification.

Cipher Suite Name                             | Value
----------------------------------------------+------------
TLS_DHE_PSK_WITH_AES_128_GCM_SHA256           | {0x00,0xAA}
TLS_DHE_PSK_WITH_AES_256_GCM_SHA384           | {0x00,0xAB}
TLS_DHE_PSK_WITH_AES_128_CCM                  | {0xC0,0xA6}
TLS_DHE_PSK_WITH_AES_256_CCM                  | {0xC0,0xA7}
TLS_PSK_DHE_WITH_AES_128_CCM_8                | {0xC0,0xAA}
TLS_PSK_DHE_WITH_AES_256_CCM_8                | {0xC0,0xAB}
TLS_ECDHE_PSK_WITH_AES_128_GCM_SHA256         | {TBD}
TLS_ECDHE_PSK_WITH_AES_256_GCM_SHA384         | {TBD}
TLS_ECDHE_PSK_WITH_AES_128_CCM_8_SHA256       | {TBD}
TLS_ECDHE_PSK_WITH_AES_128_CCM_SHA256         | {TBD}
TLS_ECDHE_PSK_WITH_AES_256_CCM_SHA384         | {TBD}
TLS_ECDHE_PSK_WITH_CHACHA20_POLY1305_SHA256   | {0xCC,0xAC}
TLS_DHE_PSK_WITH_CHACHA20_POLY1305_SHA256     | {0xCC,0xAD}

• Add the following:
  
  WARNING: Cryptographic algorithms will be broken or weakened over time. Blindly implementing cipher suites listed here is not advised. Implementers and users need to check that the cryptographic algorithms listed continue to provide the expected level of security.
  
  Note(1): Although TLS 1.3 uses the same cipher suite space as previous versions of TLS, TLS 1.3 cipher suites are defined differently, only specifying the symmetric ciphers, and cannot be used for TLS 1.2. Similarly, TLS 1.2 and lower cipher suites cannot be used with TLS 1.3.
  
  Note(2): Cipher suites marked as “Yes” are those allocated via Standards Track RFCs. Cipher suites marked as “No” are not; cipher suites marked “No” range from “good” to “bad” from a cryptographic standpoint.
  
  Note(3): The designated expert [RFC5226] only ensures that the specification is publicly available.

8. TLS Supported Groups

Add a “Recommended” column with a “Yes” for secp256r1, secp384r1, x25519, and x448 while all others are “No”. These “Yes” groups are taken from Standards Track RFCs. Not all groups from [I-D.ietf-tls-rfc4492bis], which is standards track, are not marked as “Yes”; these groups apply to TLS 1.3 [I-D.ietf-tls-tls13] and previous versions of TLS [I-D.ietf-tls-tls13]. A Standards Track document [RFC5226] is required to register an entry with the value “Yes”.

9. TLS ClientCertificateType Identifiers

IANA is to update the TLS ClientCertificateType Identifiers registry as follows:

• Change the registry policy to:
  
  Values in the range 0-223 are assigned via Specification Required [RFC5226]. Values 224-255 are reserved for Private Use.
• Add the following:
  
  Note: The designated expert [RFC5226] only ensures that the specification is publicly available.

10. New Session Ticket TLS Handshake Message Type

To align with TLS implementations and to align the naming nomenclature for other Handshake message types, IANA is to rename entry 4 in the TLS HandshakeType registry to “new_session_ticket (renamed from NewSessionTicket)”. IANA is to also add a reference to this document in the Reference column for entry 4 in the TLS HandshakeType registry.

11. TLS Exporter Label Registry

IANA is to add the following note to the TLS Exporter Label Registry:

Note: {{RFC5705}} defines keying material exporters for TLS in terms of the TLS PRF. {{I-D.ietf-tls-tls13}} replaced the PRF with HKDF, thus requiring a new construction. The exporter interface remains the same, however the value is computed different.

IANA is to also to add a “Recommended” column to the TLS Exporter Label registry. The table that follows has been generated by marking Standards Track RFCs as “Yes” and all others as “No”. Future exporters MUST define the value of this column. A Standards Track document [RFC5226] is required to register an extension with the value “Yes”.

IANA is also to add the following note:

Note: The designated expert {{RFC5226}} ensures that the specification is publicly available.  The expert also verifies that the label is a string consisting of printable ASCII characters beginning with "EXPORTER". IANA MUST also verify that one label is not a prefix of any other label.  For example, labels "key" or "master secretary" are forbidden.

Exporter Value
-------------------------------
client finished
server finished
master secret
key expansion
client EAP encryption
ttls keying material
ttls challenge
EXTRACTOR-dtls_srtp
EXPORTER_DTLS_OVER_SCTP
EXPORTER: teap session key seed

12. Add Missing Item to TLS Alert Registry

IANA is to add the following entry to the TLS Alert Registry (the entry was omitted from the IANA instructions in [RFC7301]):

120   no_application_protocol  Y  [RFC7301]

13. TLS Certificate Types

Add a “Recommended” column to the registry. X.509 and Raw Public Key are “Yes”. All others are “No”. A Standards Track document [RFC5226] is required to register a certificate type with the value “Yes”.

14. Orphaned Extensions

To make it clear that (D)TLS 1.3 has orphaned certain extensions (i.e., they are only applicable to version of (D)TLS prior to 1.3), IANA is to add the following to the TLS ExtensionType Values registry:

Note: The following extensions are only applicable to (D)TLS protocol vesions prior to 1.3: trusted_ca_keys, truncated_hmac, ec_point_formats, srp, status_request_v2, encrypt_then_mac, extended_master_secret, session_ticket, and renegotiation_info. These are not applicable to DTLS 1.3.

15. Orphaned Registries

To make it clear that (D)TLS 1.3 has orphaned certain registries (i.e., they are only applicable to version of (D)TLS protocol versions prior to 1.3), IANA is to:

• Add the following to the TLS Compression Method Identifiers registry [RFC3749]:
  
  Note: Value 0 (NULL) is the only value in this registry applicable to (D)TLS protocol version 1.3 or later.
• Add the following to the TLS HashAlgorithm [RFC5246] and TLS SignatureAlgorithm registries [RFC5246]:
  
  Note: The values in this registry are only applicable to (D)TLS protocol versions prior to 1.3.
• Update the “References” in the TLS Compression Method Identifiers, TLS HashAlgorithm [RFC5246] and TLS SignatureAlgorithm registries to also refer to this document.

IANA [SHALL update/has updated] the TLS HashAlgorithm Registry to list values 7-223 as “Reserved” and the TLS SignatureAlgorithm registry to list values 4-223 as “Reserved”.

16. Designated Expert Pool

Specification Required [RFC5226] registry requests are registered after a three-week review period on the (tbd but maybe tls-reg-review@ietf.org) mailing list, on the advice of one or more Designated Experts. However, to allow for the allocation of values prior to publication, the Designated Experts may approve registration once they are satisfied that such a specification will be published.

Registration requests sent to the mailing list for review SHOULD use an appropriate subject (e.g., “Request to register value in TLS bar registry”).

Within the review period, the Designated Experts will either approve or deny the registration request, communicating this decision to the review list and IANA. Denials SHOULD include an explanation and, if applicable, suggestions as to how to make the request successful. Registration requests that are undetermined for a period longer than 21 days can be brought to the IESG’s attention (using the iesg@ietf.org mailing list) for resolution.

Criteria that SHOULD be applied by the Designated Experts includes determining whether the proposed registration duplicates existing functionality, whether it is likely to be of general applicability or useful only for a single application, and whether the registration description is clear.

IANA MUST only accept registry updates from the Designated Experts and SHOULD direct all requests for registration to the review mailing list.

It is suggested that multiple Designated Experts be appointed who are able to represent the perspectives of different applications using this specification, in order to enable broadly informed review of registration decisions. In cases where a registration decision could be perceived as creating a conflict of interest for a particular Expert, that Expert SHOULD defer to the judgment of the other Experts.

17. Security Considerations

The authors are fairly certain that there are no security considerations for this document.

18. IANA Considerations

This document is entirely about changes to TLS-related IANA registries.

19. References

19.1. Normative References

19.2. Informative References

Authors' Addresses