The OpenSSL Library supports DTLS 1.3

Sep 9, 2026

OpenSSL 4.1, which will be released in October 2026, adds the Datagram Transport Layer Security (DTLS) protocol version 1.3.

Summary

According to the DTLS 1.3 standard:

DTLS is deliberately designed to be as similar to TLS as possible, both to minimize new security invention and to maximize the amount of code and infrastructure reuse.

Therefore DTLS 1.3 offers many of the same benefits of TLS 1.3 compared to the 1.2 versions of those protocols. It is faster because the protocol reduces the number of round trips during the handshake. It is also more secure because it has removed support for outdated cryptographic algorithms. DTLS also allows for the use of Post-Quantum Cryptography (PQC) algorithms which were implemented in OpenSSL 3.5.

Details

There are many resources available for developers wishing to implement DTSL 1.3 in their systems:

• OpenSSL DTLSv1.3 Guide
• Two demos:
  • demos/dtlsecho
  • demos/dtlslistenerecho
• DTLSv1.3 Design document
• TLS 1.3 wiki
• The CHANGES file.

Maintainers of DTLS 1.2 software should note that the SSL_new_listener() function now supports DTLS. DTLSv1_listen() does not support DTLS 1.3.

A good place to ask questions about DTLS 1.3 is OpenSSL Discussions.

Special recognition goes to Frederik Wedel-Heinen and Ryan Hooper for their work on this implementation.