Biblio

Deep learning-based semantic communications (DLSC) significantly improve communication efficiency by only transmitting the meaning of the data rather than a raw message. Such a novel paradigm can brace the high-demand applications with massive data transmission and connectivities, such as automatic driving and internet-of-things. However, DLSC are also highly vulnerable to various attacks, such as eavesdropping, surveillance, and spoofing, due to the openness of wireless channels and the fragility of neural models. To tackle this problem, we present SemKey, a novel physical layer key generation (PKG) scheme that aims to secure the DLSC by exploring the underlying randomness of deep learning-based semantic communication systems. To boost the generation rate of the secret key, we introduce a reconfigurable intelligent surface (RIS) and tune its elements with the randomness of semantic drifts between a transmitter and a receiver. Precisely, we first extract the random features of the semantic communication system to form the randomly varying switch sequence of the RIS-assisted channel and then employ the parallel factor-based channel detection method to perform the channel detection under RIS assistance. Experimental results show that our proposed SemKey significantly improves the secret key generation rate, potentially paving the way for physical layer security for DLSC.

Encryption schemes for network security usually require a key distribution center to share or distribute the secret keys, which is difficult to deploy in wireless networks without fixed infrastructure. A novel key generation scheme based on the physical layer can generate a shared key between a pair of correlated parties by sharing random sources. The existing physical layer key generation scheme is based on the half-duplex mode with time division duplex (TDD) mode, which makes it impossible for the correlated communication parties to detect the channel simultaneously in order to improve the channel coherence. In this paper, we propose a full-duplex physical layer key generation scheme, which allows each legal communication nodes to transmit and receive signals at the same time, in order to reduce channel probing time and increase channel coherence performance. The simulation experiments show that the proposed scheme can much outperform some typical existing schemes in terms of the key performance evaluation indicators, key disagreement rate, key generation rate, entropy of the scheme improved, and the randomness of generated keys passed the National Institute of Standards and Technology (NIST) test.