What’s New in NNG 2.1

NNG 2.1 adds hybrid post-quantum cryptography for TLS connections and support for DTLS 1.3.

Post-Quantum Cryptography

NNG now supports hybrid post-quantum key exchange for TLS 1.3 and DTLS 1.3 connections, including the TLS and DTLS transports, HTTPS, and secure WebSockets. Hybrid groups such as X25519MLKEM768 combine classical elliptic-curve key exchange with the post-quantum ML-KEM key encapsulation mechanism. Support depends on the selected TLS engine and its build configuration.

Applications can require hybrid post-quantum key exchange using the new nng_tls_config_groups API with a hybrid-only group list and a TLS or DTLS 1.3 version restriction. OpenSSL 3.5 and newer support these groups for TLS; DTLS requires OpenSSL 4.1 or newer with DTLS 1.3 enabled. wolfSSL requires a build with ML-KEM and hybrid support enabled, as well as DTLS 1.3 support when using DTLS.

Hybrid key exchange works with existing RSA or ECDSA certificates; certificate authentication continues to use those classical algorithms. See Requiring Hybrid Post-Quantum Key Exchange for configuration examples and engine requirements.

DTLS 1.3 Support

The DTLS transport is now supported rather than experimental. It provides encrypted, authenticated, message-oriented communication over unicast UDP when TLS support and the DTLS transport build option are enabled. It supports DTLS 1.3 as well as DTLS 1.2. DTLS 1.3 is available with wolfSSL 5.9.1 or newer built with DTLS 1.3 enabled, and with OpenSSL 4.1 or newer built with DTLS 1.3 enabled. Mbed TLS and earlier OpenSSL releases continue to support DTLS 1.2.

The default TLS configuration negotiates the highest mutually supported DTLS version. Applications can use nng_tls_config_version to require DTLS 1.3. See the DTLS transport reference for engine requirements and message size limits.