Internet-Draft | ECDHE-MLKEM | September 2024 |
Kwiatkowski, et al. | Expires 14 March 2025 | [Page] |
This draft defines two hybrid key agreements for TLS 1.3: X25519MLKEM768 and SecP256r1MLKEM768, which combine a post-quantum KEM with an elliptic curve Diffie-Hellman (ECDHE).¶
This note is to be removed before publishing as an RFC.¶
The latest revision of this draft can be found at https://post-quantum-cryptography.github.io/draft-kwiatkowski-tls-ecdhe-mlkem/. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-kwiatkowski-tls-ecdhe-mlkem/.¶
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Source for this draft and an issue tracker can be found at https://github.com/post-quantum-cryptography/draft-kwiatkowski-tls-ecdhe-mlkem.¶
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ML-KEM is a key encapsulation method (KEM) defined in the [FIPS203]. It is designed to withstand cryptanalytic attacks from quantum computers.¶
This document introduces two new supported groups for hybrid post-quantum key agreements in TLS 1.3: X25519MLKEM768 and SecP256r1MLKEM768. Both combine ML-KEM-768 with ECDH in the manner of [hybrid].¶
The first one uses X25519 [rfc7748] and is an update to X25519Kyber768Draft00 [xyber], the most widely deployed PQ/T hybrid combiner for TLS v1.3 deployed in 2024.¶
The second one uses secp256r1 (NIST P-256) [ECDSA] [DSS]. The goal of this group is to support a use case that requires both shared secrets to be generated by FIPS-approved mechanisms.¶
Both constructions aim to provide a FIPS-approved key-establishment scheme (as per [SP56C]).¶
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 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
Both groups enable the derivation of TLS session keys using FIPS-approved schemes. NIST's special publication 800-56Cr2 [SP56C] approves the usage of HKDF [HKDF] with two distinct shared secrets, with the condition that the first one is computed by a FIPS-approved key-establishment scheme. FIPS also requires a certified implementation of the scheme, which will remain more ubiqutous for secp256r1 in the coming years.¶
For this reason we put the ML-KEM-768 shared secret first in X25519MLKEM768, and the secp256r1 shared secret first in SecP256r1MLKEM768.¶
The same security considerations as those described in [hybrid] apply to the approach used by this document. The security analysis relies crucially on the TLS 1.3 message transcript, and one cannot assume a similar hybridisation is secure in other protocols.¶
Implementers are encouraged to use implementations resistant to side-channel attacks, especially those that can be applied by remote attackers.¶
This document requests/registers two new entries to the TLS Supported Groups registry, according to the procedures in Section 6 of [tlsiana]. These identifiers are to be used with the final, ratified by NIST, version of ML-KEM which is specified in [FIPS203].¶
This document obsoletes 25497 and 25498 in the TLS Supported Groups registry.¶
draft-kwiatkowski-tls-ecdhe-mlkem-02:¶
draft-kwiatkowski-tls-ecdhe-mlkem-01:¶
Add X25519MLKEM768¶
draft-kwiatkowski-tls-ecdhe-mlkem-00:¶
draft-kwiatkowski-tls-ecdhe-kyber-01: Fix size of key shares generated by the client and the server¶
draft-kwiatkowski-tls-ecdhe-kyber-00: updates following IANA review¶