Keywords
Post-quantum crypto, smart lock, Raspberry Pi

Technologies
Raspberry Pi, Android, Flask, ML-DSA, PCA9685

This project develops a secure smart lock for an HonourBox: a community drop-off and retrieval box for local deliveries and shared access. The aim was to investigate whether post-quantum cryptography could be made practical on low-cost embedded hardware while still supporting real physical access control. A classical ECDSA baseline and a post-quantum ML-DSA implementation were developed and compared on Raspberry Pi hardware to study both security and performance.

The final prototype combines an Android app, a local Flask backend, a Raspberry Pi lock controller, a servo-actuated latch, and a reed-switch lid sensor. Lightweight optimisations, including CBOR encoding, challenge batching, caching, and pre-warming, reduced payload size and unlock latency significantly. The system now supports authenticated unlock, lid-open detection, lid-close detection, and automatic relocking. The result is a practical working quantum-safe access-control prototype that shows post-quantum security can be integrated with real embedded hardware for future community delivery and unattended access systems.