Type Safe OCaml Bindings for the Open Quantum Safe Post-Quantum Cryptography Library

Abstract

The finalization of NIST post-quantum cryptography (PQC) standards necessitates the immediate migration of security-critical ecosystems to quantum-resistant algorithms. Despite OCaml powering high-assurance security infrastructure such as MirageOS unikernels, the Tezos blockchain, and NetHSM hardware security modules, a complete and type-safe PQC implementation has been historically absent from its ecosystem. This paper presents ocaml-liboqs, the first OCaml bindings to the Open Quantum Safe liboqs library, providing mathematically sound, type-safe access to all NIST-standardized PQC algorithms. We propose a rigorous two-layer architecture: a low-level ctypes Cstubs binding layer with near-zero Foreign Function Interface (FFI) overhead (<10 ns per call), and a high-level layer exploiting OCaml's module system. By leveraging abstract types, phantom types, and functors, the API enforces cryptographic correctness and prevents cross-algorithm confusion attacks entirely at compile time. Furthermore, we address the critical issue of secret key proliferation in managed memory environments by implementing unmanaged, non-movable memory buffers via Bigarray, neutralizing garbage collectors (GC) copying vulnerabilities and memory-dump attacks. Performance evaluation demonstrates that FFI overhead is negligible (<0.05%) relative to PQC operation times, while memory profiling confirms zero GC-induced secret leakage. A comprehensive comparative analysis against existing liboqs bindings for Python, Rust, Go, C++, Java, and. NET reveals that OCaml's type system provides the strongest static safety guarantees, uniquely encoding algorithm identity and key lifecycle constraints into the type system. Finally, we explore integration pathways for hybrid quantum-resistant cryptography within the MirageOS ecosystem, addressing Maximum Transmission Unit (MTU) fragmentation challenges in TLS 1.3, and establish a foundation for formally verified native OCaml PQC implementations.