Failure-Aware Hybrid Key Combiners with Composable, Reactive Security

Build a 3-source key combiner that continuously monitors indicators of component health (e.g., QKD post-processing error/leakage metrics, PQ KEM decryption-failure telemetry, entropy tests for classical KEX) and automatically rebalances or excludes components while maintaining provable security. Formalize a security model for “reactive composition” where one or more sources may degrade or leak over time, and prove composability in the quantum random oracle model (QROM). This idea upgrades existing combiners into security primitives with built-in failure sensing and adaptive trust weighting, providing composition theorems that tolerate non-idealities including correlated leaks and time-varying decryption-failure rates. The approach addresses practical issues such as fluctuating QKD links, side channels in PQ implementations, and legacy KEX retention, enabling a provably secure combiner that fails gracefully and offers quantum resilience without brittle assumptions. The impact includes a new class of failure-aware hybrid primitives with standard security reductions and practical FPGA/SoC prototypes for constrained devices.

References:

1. Hybrid Keys in Practice: Combining Classical, Quantum and Post-Quantum Cryptography. Sara Ricci, P. Dobiáš, L. Malina, J. Hajny, Petr Jedlicka (2024). IEEE Access.
2. Quantum Key Distribution Optimization: Reducing Communication Overhead in Post-Processing Steps. Ashutosh Bhatia, S. Bitragunta, Kamlesh Tiwari (2024). IEEE Region 10 Conference.