]> IANA Registry Updates for TLS and DTLS Venafi
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Security Transport Layer Security Internet-Draft This document updates the changes to TLS and DTLS IANA registries made in RFC 8447. It adds a new value "D" for discouraged to the recommended column of the selected TLS registries. This document updates the following RFCs: 3749, 5077, 4680, 5246, 5705, 5878, 6520, 7301, and 8447. About This Document Status information for this document may be found at . Discussion of this document takes place on the Transport Layer Security Working Group mailing list (), which is archived at . Subscribe at . Source for this draft and an issue tracker can be found at .
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 updates the "Recommended" column in TLS registries to define a third value "D" for items that are discouraged.
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.
Adding "Recommended" Column 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 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 it 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. Implementers SHOULD consult the linked references associated with the item to determine the conditions under which it SHOULD NOT or MUST NOT be used.
Setting a value to "Y" or "D" in the "Recommended" column requires IETF Standards Action . Any state transition to or from a "Y" or "D" value requires IESG Apporval. 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' vaue 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.
TLS ExtensionType Values In order to refect the changes in the Recommended column allocation, IANA SHALL update the TLS ExtensionType Values registry as follows:
  • Change the registration procedure to:
  • 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. A reference to this document SHALL be added to 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 .
TLS Cipher Suites Registry In order to refect the changes in the Recommended column allocation, IANA SHALL update the TLS ExtensionType Values registry as follows:
  • Change the registration procedure to:
  • 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. A reference to this document SHALL be added to these entries.
Value Cipher Suite Name Recommeded
0x00,0x01 TLS_RSA_WITH_NULL_MD5 D
0x00,0x02 TLS_RSA_WITH_NULL_SHA D
0x00,0x03 TLS_RSA_EXPORT_WITH_RC4_40_MD5 D
0x00,0x04 TLS_RSA_WITH_RC4_128_MD5 D
0x00,0x05 TLS_RSA_WITH_RC4_128_SHA D
0x00,0x06 TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5 D
0x00,0x07 TLS_RSA_WITH_IDEA_CBC_SHA D
0x00,0x08 TLS_RSA_EXPORT_WITH_DES40_CBC_SHA D
0x00,0x09 TLS_RSA_WITH_DES_CBC_SHA D
0x00,0x0B TLS_DH_DSS_EXPORT_WITH_DES40_CBC_SHA D
0x00,0x0C TLS_DH_DSS_WITH_DES_CBC_SHA D
0x00,0x0D TLS_DH_DSS_WITH_3DES_EDE_CBC_SHA D
0x00,0x0E TLS_DH_RSA_EXPORT_WITH_DES40_CBC_SHA D
0x00,0x0F TLS_DH_RSA_WITH_DES_CBC_SHA D
0x00,0x11 TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA D
0x00,0x12 TLS_DHE_DSS_WITH_DES_CBC_SHA D
0x00,0x13 TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA D
0x00,0x14 TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA D
0x00,0x15 TLS_DHE_RSA_WITH_DES_CBC_SHA D
0x00,0x17 TLS_DH_anon_EXPORT_WITH_RC4_40_MD5 D
0x00,0x18 TLS_DH_anon_WITH_RC4_128_MD5 D
0x00,0x19 TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA D
0x00,0x1A TLS_DH_anon_WITH_DES_CBC_SHA D
0x00,0x1B TLS_DH_anon_WITH_3DES_EDE_CBC_SHA D
0x00,0x19 TLS_DH_anon_EXPORT_WITH_DES40_CBC_SHA D
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
0x00,0x23 TLS_KRB5_WITH_3DES_EDE_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
0x00,0x8A TLS_PSK_WITH_RC4_128_SHA D
0x00,0x8E TLS_DHE_PSK_WITH_RC4_128_SHA D
0x00,0x92 TLS_RSA_PSK_WITH_RC4_128_SHA D
0xC0,0x02 TLS_ECDH_ECDSA_WITH_RC4_128_SHA D
0xC0,0x07 TLS_ECDHE_ECDSA_WITH_RC4_128_SHA D
0xC0,0x0C TLS_ECDH_RSA_WITH_RC4_128_SHA D
0xC0,0x11 TLS_ECDHE_RSA_WITH_RC4_128_SHA D
0xC0,0x16 TLS_ECDH_anon_WITH_RC4_128_SHA D
0xC0,0x33 TLS_ECDHE_PSK_WITH_RC4_128_SHA D
  • Update note on the recommended column with text in .
TLS Supported Groups In order to refect the changes in the Recommended column allocation, IANA SHALL update the TLS Supported Groups registry as follows:
  • Update the registration policy 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 Exporter Labels Registry This document updates the registration procedure for the TLS Exporter registry and updates the Recommended column allocation. IANA SHALL 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 highly 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 In order to refect the changes in the Recommended column allocation, IANA SHALL update the the TLS Certificate Types registry as follows:
  • Change the registration procedure 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 .
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 refect the changes in the Recommended column allocation, IANA SHALL update the TLS HashAlgorithm Registry 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 Descsription 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 refect the changes in the Recommended column allocation, IANA SHALL update the TLS SignatureAlgorithm registry 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 Descsription 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 ClientCertificateTypes 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 SHALL update the TLS ClientCertificateTypes registry as follows:
  • Update the registration procedure to include:
  • Add a reference to this document under the reference heading.
  • Update the TLS ClientCertificateTypes registry to add a "Recommended" column as follows:
Value Descsription 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 refect the changes in the Recommended column allocation, IANA SHALL 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 .
Security Considerations The change to Specification Required from IETF Review lowers the amount of review provided by the WG for cipher suites and supported groups. This change reflects reality in that the 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.
Normative References IANA Registry Updates for TLS and DTLS This document describes a number of changes to TLS and DTLS IANA registries that range from adding notes to the registry all the way to changing the registration policy. These changes were mostly motivated by WG review of the TLS- and DTLS-related registries undertaken as part of the TLS 1.3 development process. This document updates the following RFCs: 3749, 5077, 4680, 5246, 5705, 5878, 6520, and 7301. Key words for use in RFCs to Indicate Requirement Levels In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Guidelines for Writing an IANA Considerations Section in RFCs Many protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA). To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry. This is the third edition of this document; it obsoletes RFC 5226. Deprecating Obsolete Key Exchange Methods in TLS Apple, Inc. This document makes several prescriptions regarding the following key exchange methods in TLS, most of which have been superseded by better options: Deprecating TLS 1.0 and TLS 1.1 This document formally deprecates Transport Layer Security (TLS) versions 1.0 (RFC 2246) and 1.1 (RFC 4346). Accordingly, those documents have been moved to Historic status. These versions lack support for current and recommended cryptographic algorithms and mechanisms, and various government and industry profiles of applications using TLS now mandate avoiding these old TLS versions. TLS version 1.2 became the recommended version for IETF protocols in 2008 (subsequently being obsoleted by TLS version 1.3 in 2018), providing sufficient time to transition away from older versions. Removing support for older versions from implementations reduces the attack surface, reduces opportunity for misconfiguration, and streamlines library and product maintenance. This document also deprecates Datagram TLS (DTLS) version 1.0 (RFC 4347) but not DTLS version 1.2, and there is no DTLS version 1.1. This document updates many RFCs that normatively refer to TLS version 1.0 or TLS version 1.1, as described herein. This document also updates the best practices for TLS usage in RFC 7525; hence, it is part of BCP 195.