Achieving Secure and Fresh Information Updates via Short-Packet Communications

Enhancing the security and freshness of timely status update systems within next generation ultra-reliable and low-latency communications (xURLLC) demands in-depth exploration. In this letter, we focus on a security-aware information update system, where a confidential source transmits updates to a legitimate user via short-packet communications (SPC), with an eavesdropper attempting to wiretap. For this scenario, we propose a novel metric, age-of-secure-information (AoSI) to capture the security-freshness tradeoff. Analyzing the evolution of AoSI, we derive the simplified average AoSI and formulate an optimization problem minimizing it via allocating the blocklength of each update period. Via convex approximation, we propose an iterative algorithm to obtain solutions. Evaluations on system performance are presented via simulations.