Secure Transmission with Different Security Requirements Based on Covert Communication and Information-Theoretic Security in Presence of Friendly Jammer

In this paper, we investigate joint information-theoretic security and covert communication on a network in the presence of a single transmitter (Alice), a friendly jammer, a single untrusted user, two legitimate users, and a single warden of the channel (Willie). In the considered network, one of the authorized users, Bob, needs a secure and covert communication, and therefore his message must be sent securely, and at the same time, the existence of his communication with the transmitter should not be detected by the channel's warden, Willie, Meanwhile, another authorized user, Carol, needs covert communication. The purpose of secure communication is to prevent the message being decoded by the untrusted user who is present on the network, which leads us to use one of the physical layer security methods, named the secure transmission of information theory. In some cases, in addition to protecting the content of the message, it is important for the user that the existence of the transmission not being detected by an adversary, which leads us to covert communication. In the proposed network model, it is assumed that for covert communication requirements, Alice will not send any messages to legitimate users in one time slot and in another time slot will send to them both (Bob and Carol). One of the main challenges in covert communication is low transmission rate, because we have to reduce the transmission power such that the main message get hide in background noise.