Reconfigurable Intelligent Surface-Aided Secure Task-Oriented Communication

Reconfigurable intelligent surfaces (RISs) have been widely applied in physical layer security to secure wireless transmission. However, most existing works focus solely on improving security performance while neglecting task-related objectives, which can lead to degraded performance under challenging communication conditions. In this letter, we propose a RIS-assisted secure task-oriented communication system that simultaneously improves task execution at the legitimate receiver and ensures secure transmission. To solve the resulting non-convex optimization problem, we develop an alternating optimization algorithm that leverages block gradient projection for transmit precoder design and reflecting gradient projection for RIS configuration. Simulation results demonstrate that the proposed framework effectively guarantees both classification task performance and communication security.