6G aims to achieve high-data rates while enhancing security. Terahertz (THz) technologies will be pivotal in 6G due to their higher frequencies and line-of-sight (LoS) propagation characteristics. However, these advantages can also pose challenges and expose THz communication to security risks. This paper thoroughly investigates the security challenges, explores potential solutions, and identifies existing research gaps in THz communications. The unique characteristics of the THz frequency band present significant hurdles, such as path loss, beam scattering, and vulnerability to interference and side-channel attacks. We discuss current mitigation strategies and emphasize the need for further research to bolster the security and reliability of terahertz communication systems.

With the increasing connectivity of critical infrastructures through wireless technologies, the importance of edge computing is increasing many-folds. Edge computing has become an important phenomenon combining the strengths of distributed computing technologies with those of telecommunication technologies. Therefore, new technological breakthroughs are happening in the realm of edge computing for critical environments, such as the next generation underground and open-pit mining. Since the mining technologies are moving at faster pace towards digitization leveraging on connectivity technologies, edge computing plays a crucial role in bringing computing and connectivity into mines to provide latency- and security-critical services on site. In this article, we study how edge computing fulfills the needs of critical environments, focusing on mining environments, and provide important insight into future research directions.

Terahertz (THz) frequency band and free-space optical (FSO) communication can be proven potential solutions to the spectrum scarcity challenges in the emerging applications in the 6G. In this direction, a mixed THz-FSO relaying system is proposed in this paper. It is assumed that both THz and FSO links encounter fading effects and pointing errors, where the THz link is modeled using α-μ distribution while Málaga (M) distribution is used to characterize the FSO link. Particularly, we conduct the physical layer security (PLS) analysis and derive the secure outage probability into closed-form for two scenarios: 1) THz eavesdropping attack and 2) FSO eavesdropping attack. The effect of THz and FSO links parameters on the secrecy performance are then further investigated in detail. The results show that the security attacks on FSO links are more severe than those on THz links. Interestingly, the improved THz channel conditions adversely affect the security of the proposed mixed THz-FSO system, whereas better FSO channel conditions provide enhanced secrecy.