  Sixth-generation (6G) networks pose substantial security risks because
confidential information is transmitted over wireless channels with a broadcast
nature, and various attack vectors emerge. Physical layer security (PLS)
exploits the dynamic characteristics of wireless environments to provide secure
communications, while reconfigurable intelligent surfaces (RISs) can facilitate
PLS by controlling wireless transmissions. With RIS-aided PLS, a lightweight
security solution can be designed for low-end Internet of Things (IoT) devices,
depending on the design scenario and communication objective. This article
discusses RIS-aided PLS designs for 6G-IoT networks against eavesdropping and
jamming attacks. The theoretical background and literature review of RIS-aided
PLS are discussed, and design solutions related to resource allocation,
beamforming, artificial noise, and cooperative communication are presented. We
provide simulation results to show the effectiveness of RIS in terms of PLS. In
addition, we examine the research issues and possible solutions for RIS
modeling, channel modeling and estimation, optimization, and machine learning.
Finally, we discuss recent advances, including STAR-RIS and malicious RIS.
