The OpenSSL library has announced the release of version 4.0.0, which includes implementations of TLS protocols and various encryption algorithms. This release is considered a regular support release with updates being released over a 13-month period. Legacy branches of OpenSSL 3.6, 3.5 LTS, 3.4, and 3.0 LTS will continue to receive support until November 2026, April 2030, October 2026, and September 2026, respectively. The project code is distributed under the Apache 2.0 license.
Some of the key innovations in OpenSSL 4.0.0 include:
- Support for the TLS extension ECH (Encrypted ClientHello, RFC 9849), designed to encrypt information about TLS session parameters, such as the requested domain name, unlike the ESNI extension. The entire TLS ClientHello message is encrypted in ECH, providing enhanced security.
- Addition of support for the digital signature generation algorithm sm2sig_sm3, the curveSM2 key exchange group, and the curveSM2MLKEM768 post-quantum group based on crypto-algorithms standardized in China SM2.
- Inclusion of the cryptographic hashing function cSHAKE, which is based on the SHA-3 algorithm and allows for the generation of different hashes from the same input data to prevent data reuse attacks.
- Introduction of the hybrid “ML-DSA-MU” algorithm that combines the post-quantum digital signature generation algorithm ML-DSA (CRYSTALS-Dilithium) with the classic SHAKE256 hash function.
- Adding support for HMAC-SHA-based SNMP KDF and AES-CM-based SRTP KDF key generation functions used in the SNMPv3 and SRTP network protocols for cryptographic key generation.
- Discontinuation of support for SSLv3 and SSLv2 Client Hello, as well as removal of support for dynamically loaded engines in favor of using connected providers.
/Reports, release notes, official announcements.