Performance Analysis of Physical Layer Security Secrecy Key Generation in Indoor Environment

The heterogeneous nature of the Sixth-Generation (6 G) communication systems, jointly with the rapid expansion of sensitive applications, bring several challenges to systems security. The Secrecy Key Generation (SKG) is a Physical Layer Security (PLS) technique in which two legitimate nodes negotiate a session key, taking advantage of the physical layer phenomena as a source of entropy. In this contribution, we investigate the impact of Uniform Linear Array (ULA) dipole spacing on the SKG performance considering an indoor application environment. We considered two legitimate nodes, i.e., Alice and Bob, that adopt the SKG protocol to negotiate their session key. A malicious node, i.e., Eve, tries to eavesdrop on the communication to obtain the key by performing the on-the-shoulder attack. Results demonstrate that smaller dipole spacings, i.e., dleq 0.5 λ result in lower channel and key correlations between Eve and the legitimate nodes, enhancing security. Larger spacings, however, create periodic zones of moderate correlation, potentially aiding Eve under certain angular positions.