Age of Trust (AoT): A Continuous Verification Framework for Wireless Networks

TL;DR

This paper introduces the age of trust (AoT), a new metric for quantifying trust degradation over time in wireless networks, and proposes optimization schemes to balance trust verification and transmission efficiency.

Contribution

It presents the AoT framework, formulates a bi-objective optimization problem, and develops verification schemes for single and multiple access scenarios in wireless networks.

Findings

AoT effectively captures trust degradation over time.

Proposed schemes balance trust verification and throughput.

Numerical results demonstrate fair trade-offs achieved.

Abstract

Zero Trust is a new security vision for 6G networks that emphasises the philosophy of never trust and always verify. However, there is a fundamental trade-off between the wireless transmission efficiency and the trust level, which is reflected by the verification interval and its adaptation strategy. More importantly, the mathematical framework to characterise the trust level of the adaptive verification strategy is still missing. Inspired by this vision, we propose a concept called age of trust (AoT) to capture the characteristics of the trust level degrading over time, with the definition of the time elapsed since the last verification of the target user's trust plus the initial age, which depends on the trust level evaluated at that verification. The higher the trust level, the lower the initial age. To evaluate the trust level in the long term, the average AoT is used. We then investigate how to find a compromise between average AoT and wireless transmission efficiency with limited resources. In particular, we address the bi-objective optimization (BOO) problem between average AoT and throughput over a single link with arbitrary service process, where the identity of the receiver is constantly verified, and we devise a periodic verification scheme and a Q-learning-based scheme for constant process and random process, respectively. We also tackle the BOO problem in a multiple random access scenario, where a trust-enhanced frame-slotted ALOHA is designed. Finally, the numerical results show that our proposals can achieve a fair compromise between trust level and wireless transmission efficiency, and thus have a wide application prospect in various zero-trust architectures.