Publikation
Keep Private Networks Private II: Wideband Secret Key Generation on a Real 5G NR Testbed
Sachinkumar B Mallikarjun; Christoph Lipps; Marvin Reski; Sneha Bhattacharjee; Andreas Weinand; Hans Dieter Schotten
In: 22nd International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob). IEEE International Conference on Wireless and Mobile Computing, Networking And Communications (WiMob-2026), October 14-16, Avignon, France, IEEE, 10/2026.
Zusammenfassung
Secret Key Generation (SKG) from wireless channel reciprocity has been demonstrated on WiFi, LTE, and LoRaWAN. SKG feasibility on real 5G New Radio (NR) hardware, using wideband channel estimates from uplink Sounding Reference Signals (SRS) and downlink Channel State Information Reference Signals (CSI-RS), is examined in this work. An overthe-air testbed built from OpenAirInterface (OAI) gNB and nrUE instances on USRP software-defined radios operates at 3.75 GHz (n78) with 40 MHz bandwidth, and frequency-domain estimates are captured at both endpoints across thirteen lineof-sight and non-line-of-sight scenarios in SISO and MIMO antenna configurations. An asymmetry in the subcarrier ordering of OAI channel estimates is identified and resolved by an automatic orientation detector, which restores reciprocity without
manual intervention. An offline symmetric pipeline of reciprocity enhancement, quantisation, information reconciliation, privacy amplification, and key verification then yields matching 256-bit keys in every scenario, reducing the bit disagreement rate from 9.3–31.6% to 0% from 571 to 6,592 aligned channel observations at an implied key rate of approximately 1,320 bps. Per-bit Shannon entropy is 0.991 to 1.000, 11 of 12 applicable NIST SP 800-22 tests pass, and an inter-session Hamming distance of 48.8% is close to the 50% expected for independent keys.
