A Double-Edged Sword: Impacts of RIS on Secure Communications in IoT

The Internet of Things (IoT) within 6G wireless systems is anticipated to enable ubiquitous wireless machine-type communication and extensive information collection. Owing to the broadcast nature of wireless transmission, IoT networks are vulnerable to various passive and active security threats. Reconfigurable intelligent surfaces (RISs), capable of smartly reconfiguring propagation environments, have been proposed as a solution to these security challenges. RISs can play either a constructive or destructive role depending on whether they are controlled by legitimate users or adversaries; thus, they can be utilized to enhance or diminish secrecy performance for IoT networks. Specifically, by leveraging RIS as a tool, it can enhance the secrecy rate, secret key generation rate, and signal-to-interference-noise ratio (SINR). Conversely, RISs can also be weaponized to compromise secrecy transmission via pilot spoofing, reduce the secret key rate by disrupting the reciprocity of legitimate channels, and degrade the quality of service (QoS) by inducing correlated jamming. This article reviews recent studies on RIS-involved secure communications for IoT networks. Additionally, we discuss the constructive and destructive impacts of RISs. Finally, we outline promising research directions, including secure transmission schemes, attack performance analysis, and countermeasures.