IANA Registry Updates for TLS and DTLS

Introduction This document instructs IANA to make changes to a number of the IANA registries related to Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS). These changes update the changes made in . This specification adds a new value "D" for discouraged to the Recommended column of the selected TLS registries and adds a "Comment" column to all active registries that do not already have a "Comment" column. This specication also updates the registration request instructions.

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 when, and only when, they appear in all capitals, as shown here.

Updating "Recommended" Column's Values The instructions in this document update the Recommended column, originally added in to add a third value, "D", indicating that a value is "Discouraged". The permitted values of the "Recommended" column are:

Y:: Indicates that the IETF has consensus that the item is RECOMMENDED. This only means that the associated mechanism is fit for the purpose for which it was defined. Careful reading of the documentation for the mechanism is necessary to understand the applicability of that mechanism. The IETF could recommend mechanisms that have limited applicability, but will provide applicability statements that describe any limitations of the mechanism or necessary constraints on its use.
N:: Indicates that the item has not been evaluated by the IETF and that the IETF has made no statement about the suitability of the associated mechanism. This does not necessarily mean that the mechanism is flawed, only that no consensus exists. The IETF might have consensus to leave an items marked as "N" on the basis of its having limited applicability or usage constraints.
D:: Indicates that the item is discouraged. This marking could be used to identify mechanisms that might result in problems if they are used, such as a weak cryptographic algorithm or a mechanism that might cause interoperability problems in deployment. When marking a registry entry as “D”, either the References or the Comments Column MUST include sufficient information to determine why the marking has been applied. Implementers and users SHOULD consult the linked references associated with the item to determine the conditions under which the item SHOULD NOT or MUST NOT be used.

Setting a value to "Y" or "D" or transitioning the value from "Y" or "D" in the "Recommended" column requires IETF Standards Action with Expert Review or IESG Approval . Not all items defined in Standards Track RFCs need to be set to "Y" or "D". Any item not otherwise specified is set to "N". The column is blank for values that are unassigned or reserved unless specifically set.

Recommended Note Existing registries have a note on the meaning of the Recommended column. For the registries discussed in the subsequent sections this note is updated with a sentence describing the "D" value as follows:

Note:: If "Recommended" column is set to "N", it does not necessarily mean that it is flawed; rather, it indicates that the item either has not been through the IETF consensus process, has limited applicability, or is intended only for specific use cases. If the "Recommended" column is set to "D" the item is discouraged and SHOULD NOT or MUST NOT be used, depending upon the situation; consult the item’s references for clarity.

TLS ExtensionType Values Registry In order to reflect the changes in the Recommended column allocation, IANA is requested to update the TLS ExtensionType Values registry as follows:

Adjust the registration procedure related to setting the “Recommended” column as follows:

Add a reference to this document under the reference heading.
Update the "Recommended" column with the changes as listed below. Entries keep their existing "Y" and "N" entries except for the entries in following table. IANA is requested to add a reference to this document for these entries.

Value	Extension	Recommended
4	truncated_hmac	D
53	connection_id (deprecated)	D
40	Reserved	D
46	Reserved	D

Update note on the Recommended column with text in .
For the truncated_hmac, add the following link to Reference column: https://www.iacr.org/archive/asiacrypt2011/70730368/70730368.pdf
For the two Reserved values above, add the following link in the Reference column: https://mailarchive.ietf.org/arch/msg/tls-reg-review/5BD62HBFjo_AsW-Y8ohVuWEe1gI/

TLS Cipher Suites Registry Several categories of ciphersuites are discouraged for general use and are marked as "D". Ciphersuites that use NULL encryption do not provide the confidentiality normally expected of TLS. Protocols and applications are often designed to require confidentiality as a security property. These ciphersuites MUST NOT be used in those cases. Ciphersuites marked as EXPORT use weak ciphers and were deprecated in TLS 1.1 . Cipher suites marked as anon do not provide any authentication and are vulnerable to on-path attacks and are deprecated in TLS 1.1 . RC4 is a weak cipher and is deprecated in . DES and IDEA are not considered secure for general use and are deprecated in . Nor is MD5 or SHA-1 and these are deprecated in . In order to reflect the changes in the Recommended column allocation, IANA is requested to update the TLS ExtensionType Values registry as follows:

Adjust the registration procedure related to setting the “Recommended” column as follows:

Add a reference to this document under the reference heading.
Update the "Recommended" column with the changes as listed below. Entries keep their existing "Y" and "N" entries except for the entries in following table. IANA is requested to add a reference to this document for these entries. This document does not make any changes to the DTLS-OK column.

Value	Cipher Suite Name	Recommended
0x00,0x1E	TLS_KRB5_WITH_DES_CBC_SHA	D
0x00,0x20	TLS_KRB5_WITH_RC4_128_SHA	D
0x00,0x21	TLS_KRB5_WITH_IDEA_CBC_SHA	D
0x00,0x22	TLS_KRB5_WITH_DES_CBC_MD5	D
0x00,0x24	TLS_KRB5_WITH_RC4_128_MD5	D
0x00,0x25	TLS_KRB5_WITH_IDEA_CBC_MD5	D
0x00,0x26	TLS_KRB5_EXPORT_WITH_DES_CBC_40_SHA	D
0x00,0x27	TLS_KRB5_EXPORT_WITH_RC2_CBC_40_SHA	D
0x00,0x28	TLS_KRB5_EXPORT_WITH_RC4_40_SHA	D
0x00,0x29	TLS_KRB5_EXPORT_WITH_DES_CBC_40_MD5	D
0x00,0x2A	TLS_KRB5_EXPORT_WITH_RC2_CBC_40_MD5	D
0x00,0x2B	TLS_KRB5_EXPORT_WITH_RC4_40_MD5	D
0x00,0x2C	TLS_PSK_WITH_NULL_SHA	D
0x00,0x8A	TLS_PSK_WITH_RC4_128_SHA	D
0x00,0xB0	TLS_PSK_WITH_NULL_SHA256	D
0x00,0xB1	TLS_PSK_WITH_NULL_SHA384	D
0xC0,0x06	TLS_ECDHE_ECDSA_WITH_NULL_SHA	D
0xC0,0x07	TLS_ECDHE_ECDSA_WITH_RC4_128_SHA	D
0xC0,0x10	TLS_ECDHE_RSA_WITH_NULL_SHA	D
0xC0,0x11	TLS_ECDHE_RSA_WITH_RC4_128_SHA	D
0xC0,0x33	TLS_ECDHE_PSK_WITH_RC4_128_SHA	D
0xC0,0x39	TLS_ECDHE_PSK_WITH_NULL_SHA	D
0xC0,0x3A	TLS_ECDHE_PSK_WITH_NULL_SHA256	D
0xC0,0x3B	TLS_ECDHE_PSK_WITH_NULL_SHA384	D
0xC0,0xB4	TLS_SHA256_SHA256	D
0xC0,0xB5	TLS_SHA384_SHA384	D

Update note on the Recommended column with text in .

TLS Supported Groups Registry In order to reflect the changes in the Recommended column allocation, IANA is requested to update the TLS Supported Groups registry as follows:

Update the registration policy to include:

Add a reference to this document under the reference heading.
Update the "Recommended" column with the changes as listed below. Entries keep their existing "Y" and "N" entries except for the entries in following table. IANA is requested to add a reference to this document for these entries.

Value	Curve	Recommended
1	sect163k1	D
2	sect163r1	D
3	sect163r2	D
4	sect193r1	D
5	sect193r2	D
6	sect233k1	D
7	sect233r1	D
8	sect239k1	D
15	secp160k1	D
16	secp160r1	D
17	secp160r2	D
18	secp192k1	D
19	secp192r1	D
20	secp224k1	D
21	secp224r1	D

Update note on the Recommended column with text in .
Remove the "Elliptic curve groups" note from the registration procedures table.
For each of the entries above, add the following link to the Comment column: https://datatracker.ietf.org/meeting/118/materials/slides-118-tls-rfc8447bis-00

TLS Exporter Labels Registry This document updates the registration procedure for the TLS Exporter Labels registry and updates the Recommended column allocation. IANA is requested to update the TLS Exporter Labels Registry as follows:

Change the registration procedure from Specification Required to Expert Review and update it to include:

Add a reference to this document under the reference heading.
Entries keep their existing Recommended column "Y" and "N" entries
Update note on the Recommended column with text in .
Update the note on the role of the expert reviewer as follows.

Note:: The role of the designated expert is described in . Even though this registry does not require a specification, the designated expert will strongly encourage registrants to provide a link to a publicly available specification. An Internet-Draft (that is posted and never published as an RFC) or a document from another standards body, industry consortium, university site, etc. are suitable for these purposes. The expert may provide more in-depth reviews, but their approval should not be taken as an endorsement of the exporter label. 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.

TLS Certificate Types Registry In order to reflect the changes in the Recommended column allocation, IANA is requested to update the TLS Certificate Types registry as follows:

Adjust the registration procedure related to setting the “Recommended” column as follows:

Add a reference to this document under the reference heading.
Entries keep their existing Recommended column "Y" and "N" entries.
Update note on the Recommended column with text in .

TLS HashAlgorithm Registry Though TLS 1.0 and TLS 1.1 were deprecated , TLS 1.2 will be in use for some time. In order to reflect the changes in the Recommended column allocation, IANA is requested to update the TLS HashAlgorithm Registry as follows:

Update the registration procedure to include:

Add a reference to this document under the reference heading.
Update the TLS HashAlgorithm registry to add a "Recommended" column as follows:

Value	Description	Recommended
0	none	Y
1	md5	D
2	sha1	D
3	sha224	D
4	sha256	Y
5	sha384	Y
6	sha512	Y
8	Intrinsic	Y

Add note on the Recommended column with text in .

TLS SignatureAlgorithm Registry Though TLS 1.0 and TLS 1.1 were deprecated , TLS 1.2 will be in use for some time. In order to reflect the changes in the Recommended column allocation, IANA is requested to update the TLS SignatureAlgorithm registry as follows:

Update the registration procedure to include:

Add a reference to this document under the reference heading.
Update the TLS SignatureAlgorithm registry to add a "Recommended" column as follows:

Value	Description	Recommended
0	anonymous	N
1	rsa	Y
2	dsa	N
3	ecdsa	Y
7	ed25519	Y
8	ed448	Y
64	gostr34102012_256	N
65	gostr34102012_512	N

Add note on the Recommended column with text in .

TLS ClientCertificateType Identifiers Registry Though TLS 1.0 and TLS 1.1 were deprecated , TLS 1.2 will be in use for some time. In order to refect the changes in the Recommended column allocation, IANA is requested to update the TLS ClientCertificateType Identifiers registry as follows:

Update the registration procedure to include:

Add a reference to this document under the reference heading.
Update the TLS ClientCertificateType Identifiers registry to add a "Recommended" column as follows:

Value	Description	Recommended
1	rsa_sign	Y
2	dss_sign	N
3	rsa_fixed_dh	N
4	dss_fixed_dh	N
5	rsa_ephemeral_dh_RESERVED	D
6	dss_ephemeral_dh_RESERVED	D
20	fortezza_dms_RESERVED	D
64	ecdsa_sign	Y
65	rsa_fixed_ecdh	N
66	ecdsa_fixed_ecdh	N
67	gost_sign256	N
68	gost_sign512	N

Add note on the Recommended column with text in .

TLS PskKeyExchangeMode Registry In order to reflect the changes in the Recommended column allocation, IANA is requested to update the TLS PskKeyExchangeMode registry as follows:

Update the registration procedure to include:

Add a reference to this document under the reference heading.
Entries keep their existing Recommended column "Y" and "N" entries.
Update note on the Recommended column with text in .

TLS SignatureScheme Registry In order to reflect the changes in the Recommended column allocation, IANA is requested to update the TLS SignatureScheme registry as follows:

Update the registration procedure to include:

IANA is requested to add a reference to this document under the reference heading.
Entries keep their existing Recommended column "Y" and "N" entries.
Update note on the Recommended column with text in .

Adding "Comment" Column IANA is requested to add a "Comment" column to the following registries:

TLS ExtensionType Values
TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs
TLS CachedInformationType Values
TLS Certificate Compression Algorithm IDs
TLS Cipher Suites
TLS ContentType
TLS EC Point Formats
TLS EC Curve Types
TLS Supplemental Data Formats (SupplementalDataType)
TLS UserMappingType Values
TLS Authorization Data Formats
TLS Heartbeat Message Types
TLS Heartbeat Modes
TLS SignatureScheme
TLS PskKeyExchangeMode
TLS KDF Identifiers

This list of registries is all registries that do not already have a "Comment" or "Notes" column or that were not orphaned by TLS 1.3.

Expert Review of Current and Potential IETF and IRTF Documents The intent of the Specification Required choice for TLS code points is to allow for easy registration for code points associated with protocols and algorithms that are not being actively developed inside IETF or IRTF. When TLS-based technologies are being developed inside the IRTF/IETF they should be done in coordination with the TLS WG in order to provide appropriate review. For this reason, unless the TLS WG chairs indicate otherwise via email, designated experts should decline code point registrations for documents which have already been adopted or are being proposed for adoption by IETF working groups or IRTF research groups.

Registration Requests Registration requests MUST be submitted in one of two ways:

By sending email to iana@iana.org; this email SHOULD use an appropriate subject (e.g., "Request to register value in TLS bar registry").
Using the online form at https://www.iana.org/form/protocol-assignment.

Specification Required registry requests are registered after a three-week review period 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.

Security Considerations The change to Specification Required from IETF Review lowers the amount of review provided for cipher suites and supported groups. This change reflects reality in that the TLS WG essentially provided no cryptographic review of the cipher suites or supported groups. This was especially true of national cipher suites. Recommended algorithms are regarded as secure for general use at the time of registration; however, cryptographic algorithms and parameters will be broken or weakened over time. It is possible that the "Recommended" status in the registry lags behind the most recent advances in cryptanalysis. Implementers and users need to check that the cryptographic algorithms listed continue to provide the expected level of security. Designated experts ensure the specification is publicly available. They may provide more in-depth reviews. Their review should not be taken as an endorsement of the cipher suite, extension, supported group, etc.

IANA Considerations This document is entirely about changes to TLS-related IANA registries. IANA is requested to modify the note applied to all TLS Specification Required registries instructing where to send registration requests as follows: Requests for assignments from the registry's Specification Required range should be sent to the mailing list described in [This RFC, Section 16]. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.