Open Quantum Safe (liboqs + oqs-provider)

The Open Quantum Safe project, maintained by the University of Waterloo's Institute for Quantum Computing and stewarded by the Linux Foundation, is the most important open-source infrastructure project in the post-quantum cryptography ecosystem. If you are running any PQC implementation that is not a direct cloud-native service, there is a significant probability it either uses liboqs directly or was validated against it. liboqs is a C library implementing more than 30 post-quantum cryptographic schemes, including all three NIST-finalized algorithms (ML-KEM in all parameter sets, ML-DSA in all parameter sets, SLH-DSA in selected parameter sets), plus NIST-standardized alternatives like HQC, and additional schemes under ongoing evaluation. The library is designed for research, prototyping, and integration — not as a standalone TLS endpoint, but as the algorithmic foundation that other software builds on top of. The oqs-provider is the integration layer that connects liboqs to OpenSSL 3.x via the OpenSSL provider API. This is the piece that enables real-world TLS testing: any OpenSSL-based application (nginx, Apache, curl, OpenVPN, and thousands of others) can be recompiled or configured to use PQC key exchange and authentication via oqs-provider, without modifying the application itself. This has made OQS the de facto standard for enterprise PQC compatibility testing — security teams use it to verify that their existing TLS infrastructure can negotiate hybrid PQC before migrating production systems. OQS also maintains forks of OpenSSH and other widely deployed protocols with PQC support, and provides language bindings for Python, Java, Go, Rust, and Node.js through liboqs-python, liboqs-java, and similar wrapper projects. The project runs an OQS demo TLS server and maintains compatibility matrices against every major TLS client, which is used extensively by enterprise architects validating migration readiness. Android and embedded platform support is documented and tested.