Post-Quantum Security Has to Survive the Radio

The handshake has a physical footprint

A remote sensor can carry strong cryptography and still fail before useful data moves. A new University of Colorado Boulder preprint models that problem on narrow radio links, where post-quantum certificates, signatures and keys arrive as long packet trains. The authors estimate bandwidth, memory, compute time and battery draw for certificate-based authentication on an NB-IoT connection. Under their stated assumptions, a security Category 1 ML-DSA-44 and ML-KEM-512 exchange produces 334 real-world packets and consumes 10,688 millijoules for transmission and reception. The proposed shared-secret route with ephemeral ML-KEM reduces those figures to 112 packets and 3,584 millijoules.

Loss changes the result

The satellite case makes packet count more than an efficiency metric. With 10 percent independent packet loss, the paper models a 0.8 percent single-attempt success rate for a 46-packet certificate-based exchange and 23 percent for a 14-packet shared-secret exchange. Those are first-order calculations, not field measurements, and the authors spell out assumptions about packet size, throughput, retransmission and device hardware. Even so, the comparison exposes a practical post-quantum authentication problem: a secure algorithm may still miss the contact window in which the device can use it.

Key management moves to the center

The proposed design uses an existing 5G or 6G shared-secret ecosystem, a Kerberos-style key distribution center and a DTLS pre-shared-key handshake with ephemeral ML-KEM. It preserves a post-quantum key-establishment step while avoiding digital-signature certificates at the endpoint. That can ease the radio and battery load, while placing more weight on enrollment, secret storage, lifecycle controls and the trusted key-distribution service. Constrained-network PQC therefore reaches beyond algorithm selection. It changes who holds trust, which infrastructure must remain available and whether a medical sensor, asset tracker or satellite terminal can authenticate reliably at all.