TLS 1.2 is in Feature Freeze

Status of This Memo

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Table of Contents

1. Introduction

Use of TLS 1.3 [TLS13] is growing, and it fixes most known deficiencies with TLS 1.2 [TLS12], such as encrypting more of the traffic so that it is not readable by outsiders and removing most cryptographic primitives now considered weak. Importantly, TLS 1.3 enjoys robust security proofs.¶

Both versions have several extension points, so items like new cryptographic algorithms, new supported groups (formerly "named curves"), etc., can be added without defining a new protocol. This document specifies that outside of urgent security fixes, and the exceptions listed in Section 4, no changes will be approved for TLS 1.2. This prescription does not pertain to DTLS (in any DTLS version); it pertains to TLS only.¶

2. Implications for post-quantum cryptography

Cryptographically relevant quantum computers, once available, will have a huge impact on RSA, FFDH, and ECC which are currently used in TLS. In 2016, the US National Institute of Standards and Technology started a multi-year effort to standardize algorithms that will be "safe" once quantum computers are feasible [PQC]. First discussions in the IETF community happened around the same time [CFRGSLIDES].¶

In 2024 NIST released standards for [ML-KEM], [ML-DSA], and [SLH-DSA]. While industry was waiting for NIST to finish standardization, the IETF has had several efforts underway. A working group was formed in early 2023 to work on use of PQC in IETF protocols, [PQUIPWG]. Several other working groups, including TLS [TLSWG], are working on drafts to support hybrid algorithms and identifiers, for use during a transition from classic to a post-quantum world.¶

For TLS it is important to note that the focus of these efforts is exclusively TLS 1.3 or later. Put bluntly, post-quantum cryptography for TLS 1.2 WILL NOT be supported (see Section 4) at any time and anyone wishing to deploy post-quantum cryptography should expect to be using TLS 1.3.¶

3. Security Considerations

This entire document is about security, and provides post-quantum concerns as an additional reason to upgrade to TLS 1.3.¶

4. IANA Considerations

No registries [TLS13REG] are being closed by this document. Rather, this document modifies the instructions to IANA and the TLS Designed Experts to constrain what type of entries can be added.¶

There are no limits on the registrations for either of the following two registries:¶

• TLS Application-Layer Protocol Negotiation (ALPN) Protocol IDs¶

• TLS Exporter Labels¶

All other registries should have this Note added to them:

Any entry added after the IESG approves publication of {THIS RFC} is intended for TLS 1.3 or later, and makes no requirement on DTLS. Such entries should have an informal indication indication like "For TLS 1.3 or later" in that entry, such as the "Comment" column.¶

At the time of publication, the list of other registries is as follows:¶

• TLS Alerts¶

• TLS Authorization Data Formats¶

• TLS CachedInformationType Values¶

• TLS Certificate Compression Algorithm IDs¶

• TLS Certificate Status Types¶

• TLS Certificate Types¶

• TLS Cipher Suites¶

• TLS ClientCertificateType Identifiers¶

• TLS ContentType¶

• TLS EC Curve Types¶

• TLS EC Point Formats¶

• TLS ExtensionType Values¶

• TLS HandshakeType¶

• TLS HashAlgorithm¶

• TLS Heartbeat Message Types¶

• TLS Heartbeat Modes¶

• TLS KDF Identifiers¶

• TLS PskKeyExchangeMode¶

• TLS SignatureAlgorithm¶

• TLS SignatureScheme¶

• TLS Supplemental Data Formats (SupplementalDataType)¶

• TLS Supported Groups¶

• TLS UserMappingType Values¶

Any registries created after this document is approved for publication should indicate whether the actions defined here are applicable.¶

5. References

Acknowledgments

We gratefully acknowledge Amanda Baber, David Dong, and Sabrina Tanamal of IANA for their help in revising and clarifying Section 4.¶

Authors' Addresses