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In this paper, an image encryption technique is proposed to encrypt the images by using a 2D Logistic map with the SHA-256 sequence generator. The initial conditions and control parameters of the chaotic maps served as the key for the cryptosystem, and were made dependent on the plain image through the SHA-256 protocol. The internal loop of the proposed image encryption method is made of 2D logistic permutation, and 2D logistic diffusion. In order the proposed system performance, widely known and accepted metrics as keyspace, key sensitivity, histogram, correlation and entropy were computed. Experimental results showed that the proposed approach was highly key sensitive and exhibited a good resistance against brute-force and statistical attacks. The cryptosystem presented in this part was designed to ensure the safe exchange of medical images on the 5G telecommunication network using IoHT in the interconnexion of different hospital services. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the stability of the synchronous state in a complex network using the master stability function technique. We use the extended Hindmarsh–Rose neuronal model including time delayed electrical, chemical, and hybrid couplings. We find the corresponding master stability equation that describes the whole dynamics for each coupling mode. From the maximum Lyapunov exponent, we deduce the stability state for each coupling mode. We observe that for electrical coupling, there exists a mixing between stable and unstable states. For a good setting of some system parameters, the position and the size of unstable areas can be modified. For chemical coupling, we observe difficulties in having a stable area in the complex plane. For hybrid coupling, we observe a stable behavior in the whole system compared to the case where these couplings are considered separately. The obtained results for each coupling mode help to analyze the stability state of some network topologies by using the corresponding eigenvalues. We observe that using electrical coupling can involve a full or partial stability of the system. In the case of chemical coupling, unstable states are observed whereas in the case of hybrid interactions a full stability of the network is obtained. Temporal analysis of the global synchronization is also done for each coupling mode, and the results show that when the network is stable, the synchronization is globally observed, while in the case when it is unstable, its nodes are not globally synchronized. [ABSTRACT FROM AUTHOR]