PQClean/PQClean
FreeClean, portable, tested implementations of post-quantum cryptography
FreeFree tier
About PQClean/PQClean
PQClean is an open-source collection of clean, portable, and tested implementations of post-quantum cryptographic schemes from the NIST Post-Quantum Cryptography project. It aims to provide standalone C implementations that can be integrated into higher-level libraries like liboqs, benchmarking frameworks like SUPERCOP, embedded platforms like pqm4, and formal verification efforts. The project prioritizes code quality and security, with implementations suitable for architecture-specific optimizations and security evaluation. Note: PQClean is no longer under active maintenance and is planned to be archived as read-only in July 2026.
Key Features
Clean, portable C implementations of NIST post-quantum cryptographic schemes
Tested and high-quality code suitable for integration into libraries (liboqs), benchmarking (SUPERCOP), embedded platforms (pqm4), and formal verification
Designed for standalone use and as a starting point for architecture-specific optimizations and security evaluation
Supports both key encapsulation mechanisms (KEM) and signature schemes
Open-source and community-contributed with a focus on code quality and testing
Pros & Cons
Pros
- High-quality, tested, and portable C code that is easy to integrate
- Covers multiple NIST post-quantum algorithms (KEM and signature schemes)
- Provides standalone implementations suitable for many downstream projects
- Actively maintained for many years with a clear paper summarizing lessons learned
- Open-source with permissive licensing (public domain or similar)
Cons
- No longer under active maintenance; scheduled to be archived read-only in July 2026
- Limited to C implementations; no built-in build system for an integrated library
- Does not include benchmarking or higher-level protocol integration by itself
- Some algorithms may need to be sourced from alternative repositories (e.g., Falcon, HQC, Classic McEliece)
Best For
Integrating post-quantum cryptography into higher-level cryptographic libraries and protocolsBenchmarking post-quantum algorithm performance in frameworks like SUPERCOPDeploying post-quantum cryptography on embedded platforms (e.g., ARM Cortex-M4 via pqm4)Formal verification and security evaluation of post-quantum implementationsEducation and research in post-quantum cryptography standardization
FAQ
What is PQClean?
PQClean is a collection of clean, portable, and tested implementations of post-quantum cryptographic schemes from the NIST Post-Quantum Cryptography project. It provides standalone C code that can be integrated into libraries, benchmarking frameworks, and embedded platforms.
What types of algorithms are included?
PQClean includes key encapsulation mechanisms (KEM) and signature schemes from the NIST project. The repository contains directories for crypto_kem and crypto_sign with various parameter sets.
Is PQClean still actively maintained?
No. As of the repository notice, PQClean is no longer under active maintenance and is planned to be archived as read-only in July 2026. For maintained implementations of standardized PQC, consider the PQ Code Package or alternative sources for specific algorithms like Falcon, HQC, and Classic McEliece.
How can I integrate PQClean into my project?
PQClean implementations are designed as standalone C files with minimal dependencies. They can be copied directly into your project and compiled. The implementations are compatible with libraries like liboqs, SUPERCOP, and pqm4.
What is the licensing for PQClean?
The repository does not specify a single license file, but implementations are generally public domain or under permissive licenses. Contributors must adhere to the coding and testing requirements outlined in CONTRIBUTING.md.