Educational Rust implementation of Hamming Quasi-Cyclic (HQC) KEM as described in the 2025-08-22 draft.

This library is for educational purposes only.

• This is an experimental implementation of a draft standard
• It has not been audited
• It is not constant-time (timing side-channels may exist)
• The API is unstable and will change without notice
• We make no security guarantees whatsoever

If you need a post-quantum KEM in production, use something else.

HQC-1, HQC-3, and HQC-5 all pass reference KATs.

Note: This crate depends on a fork of hybrid-array with HQC sizes.

# Run all tests except KATs
cargo test

# Run all KATs (use release mode since KATs are slow in debug)
cargo test --release -- --ignored

Run benchmarks with:

cargo bench --bench kem

On my MacBook Pro with Apple M2 Pro, I thought it would be humbling to benchmark this against ML-KEM from aws-lc-rs 1.15.4 at equivalent security levels. I was right. Note that these are entirely different algorithms, so the comparison isn't really fair — but neither are the numbers, so it fits.

KeyGen

Encaps

Decaps

syndrmrs is not optimized (yet!) 🤷

The structure of this crate was influenced by RustCrypto's ml-kem. This project is not affiliated with RustCrypto.

This is a personal project and is not affiliated with or endorsed by my employer.