Digital twin (DT) technology is a real-time evolving digital duplicate of a physical object or process that contains all its history. It is enabled by massive real-time multi-source data collection and analysis. While 6G is considered as an enabler of digital twins, DT can also be a facilitator for integrating AI and 6G towards reliable, pervasive and efficient intelligent technologies.

6G networks are expected to provide one-microsecond latency communication with a billion of devices expected to compete for resources 1000 times faster than current standards. Increases in network speed, heterogeneity, virtualization, better radio requirements and adaptive communications will place new demands on physical layer security. Moreover, IoT, blockchain, and artificial intelligence are enabling technologies that require rapid data rates, raising a significant burden on the network's physical layer, requiring that security must be attained at a fast pace, and that the network must be resilient to accommodate sudden changes to the configurations or the load.

There is no doubt that we are facing a wireless data explosion. Modern wireless networks need to satisfy increasing demand, but are faced with challenges such as limited spectrum, expensive resources, green communication requirements and security issues. In the age of internet of things (IoT) with massive data transfers and huge numbers of connected devices, including high-demand QoS (4G, 5G networks and beyond), signal processing is producing data sets at the gigabyte and terabyte scales.

Physical layer security is emerging as a promising means of ensuring secrecy in wireless communications. The key idea is to exploit the characteristics of wireless channels such as fading or noise to transmit a message from the source to the intended receiver while keeping this message confidential from eavesdroppers.