  Integrated sensing and communications (ISAC) systems employ dual-functional
signals to simultaneously accomplish radar sensing and wireless communication
tasks. However, ISAC systems open up new sensing security vulnerabilities to
malicious illegitimate eavesdroppers (Eves) that can also exploit the
transmitted waveform to extract sensing information from the environment. In
this paper, we investigate the beamforming design to enhance the sensing
security of an ISAC system, where the communication user (CU) serves as a
sensing Eve. Our objective is to maximize the mutual information (MI) for the
legitimate radar sensing receiver while considering the constraint of the MI
for the Eve and the quality of service to the CUs. Then, we consider the
artificial noise (AN)-aided beamforming to further enhance the sensing
security. Simulation results demonstrate that our proposed methods achieve MI
improvement of the legitimate receiver while limiting the sensing MI of the
Eve, compared with the baseline scheme, and that the utilization of AN further
contributes to sensing security.
