OpenSSL’s new alpha build speeds up post-quantum crypto

The OpenSSL project released the first alpha of OpenSSL 4.1.0, giving developers an early look at a version built for encrypted communication over unreliable connections and faster post-quantum cryptography. This marks the opening test build for a version still months from general availability.

The headline addition is support for DTLS 1.3, the latest revision of the Datagram Transport Layer Security protocol defined in RFC 9147. DTLS secures traffic sent over UDP rather than TCP, the kind of connection used by video calls, VPNs, and IoT devices where packets can arrive late or out of order. Version 1.3 brings that traffic up to the same security baseline as TLS 1.3, closing a gap where DTLS deployments had lagged behind their TCP counterparts on features like forward secrecy and reduced handshake overhead.

OpenSSL 4.1.0 alpha1 also speeds up OpenSSL’s post-quantum algorithms, the ones designed to resist attacks from future quantum computers. It adds optimized ML-DSA and ML-KEM operations for the ppc64le architecture, ML-DSA optimizations for s390x and x86_64, and AVX-512 instructions to accelerate the SHAKE hashing that ML-DSA depends on. A separate AVX-512 and VAES optimization speeds up AES-CBC decryption on x86_64 chips. None of this changes what the algorithms do. It changes how much it costs to run them, which matters as organizations start migrating production systems to post-quantum key exchange and signatures ahead of any quantum threat materializing.

A few changes will break existing setups. The tsget timestamp utility now depends on the Net::Curl::Easy Perl module instead of the unmaintained WWW::Curl::Easy, so anyone using tsget needs to install the new dependency before upgrading. The build system drops support for Windows-on-Itanium and Windows CE entirely. And the Configure script removes the no-ecdsa and no-ecdh options, because they never actually disabled those implementations. Anyone who wants to turn off elliptic curve support now uses no-ec instead.

The release adds a handful of smaller items: GREASE support under RFC 8701, which prevents TLS clients and servers from choking on unrecognized extension values; a DTLS mode for the SSL listener API; support for the IKEv2 key derivation function used in VPN negotiations; and initial support for the Elbrus2000 processor architecture used in some Russian-made systems.

OpenSSL typically runs a series of alpha and beta builds before a final version ships, so the feature list can still shift. Teams running DTLS in production, or already testing post-quantum deployments, are the ones with the clearest reason to start testing now.