### Related Work
Although this paper opened doors to future secure wireless systems integrated with SWIPT in CR-NOMA networks, the authors did not consider SUs with the ability to simultaneously receive information and harvest energy, and it was assumed that channel vectors to the eavesdroppers are known at the secondary BS, which is not always possible in practical scenarios where eavesdroppers are hidden from the secondary BS. Please note that the PS structure considered in this paper involves the optimization of PS ratios, which are coupled to the beamforming vectors in the optimization problem. In general, the mathematical algorithms used to solve optimization problems are problem-dependent. The proposed algorithms to solve the optimization problems in the aforementioned literature are developed based on specific characteristic of the problems such as objective function, type of users, type of constraints and so on. For instance, the procedures and techniques used to transform non-convex problems to convex ones will differ from system to system and depend on the assumptionsand elements considered for the optimization problem. When a system model includes new elements with other applications such as SWIPT users or CR capabilities, the previous proposed algorithms cannot be used anymore directly, and a novel algorithm needs to be developed to solve the new problem. Therefore, previous proposed algorithms for a PLS in MISO-NOMA system cannot be applied for the proposed cognitive MISO SWIPT NOMA system with AN. None of the research described above was specifically proposed to enhance the security of the secondary network in a SWIPT-assisted NOMA-CR with EH users. In addition, the proposed scheme in the paper can be applied for the security in different scenarios such as IoT systems with RF EH user where spectrum scarcity is a critical issue due to the massive deployment of IoT devices. Here, NOMA is used to achieve better connectivity and to enhance spectrum use while EH can be used for improving the energy efficiency of IoT systems [37]. Furthermore, in the case that malicious EH users exist in the system as the work in [36], where a secondary transmitter sends information signals to SUs and energy to EH user, the EH user can eavesdrop the information transmitted to secondary users because of the broadcast nature of NOMA. In this scenario, a channel state information (CSI) of the EH user is available at the secondary transmitter, which can be used for a more precise beamforming design of the AN to interfere with the malicious EH user. In addition, the SSR for the secondary users can be directly maximized in the optimization problem to improve the security in the network. On the other hand, in the paper we propose a more challenging scenario when the eavesdropper is completely hidden from the secondary transmitter and the CSI of the eavesdropper is not available. In this case, the transmission power for legitimate users is minimized to use the remaining available power to maximize the AN. In addition, there is no any impact on the system even though the eavesdropper performs energy-harvesting since the eavesdropper is not a legitimate user and the secondary transmitter does not transfer extra energy signals to satisfy some EH requirement at the eavesdropper.