To ensure the security of digital images during transmission and storage, an efficient and secure chaos-based color image encryption scheme using bit-level permutation is proposed. Our proposed image encryption algorithm belongs to symmetric cryptography. Here, we process three color components simultaneously instead of individually, and consider the correlation between them. We propose a novel bit-level permutation algorithm that contains three parts: a plain-image related rows and columns substitution, a pixel-level roll shift part, and a bit-level cyclic shift part. In the plain-related rows and columns substitution part, we involve the plain-image information to generate a control sequence by using a skew tent system. This process ensures that the correlation between three color components can be totally broken, and our cryptosystem has enough plain-image sensitivity to resist the differential attack. In the pixel-level roll shift part and bit-level cyclic shift part, we have a fully bit-level permutation controlled by two sequences using a Rucklidge system. The simulation and some common security analyses are given. Test results show that our proposed scheme has good security performance and a speed advantage compared to other works.

This paper investigates the downlink achievable spectral efficiency (SE) and energy efficiency (EE) of massive MIMO for hybrid architectures based on phase shifters, where the base station (BS) has perfect channel state information and baseband processing is done zero-forcing precoding. We derive an approximated upper bound on the achievable SE for hybrid architecture with ideal phase shifters. Based on the derived analytical expression, we find that the total achievable SE increases with the number of BS antennas and users, and the signal-to-noise ratio (SNR). In order to acquire the required limited feedback, we propose an algorithm to generate the corresponding quantized matrix and study hybrid architectures with quantized phase shifters. Compared to fulldigital architectures, results show that hybrid architectures enjoy a much higher achievable EE in massive MIMO systems, whereas its achievable SE is inferior to full-digital architectures. In addition, results also showcase that the achievable SE of hybrid architectures can be improved by increasing the bits of phase shifters, and there exists an optimal SNR and antenna number to maximize the achievable EE of the system.

With the development of mobile communication network, especially 5G today and 6G in the future, the security and privacy of digital images are important in network applications. Meanwhile, high resolution images will take up a lot of bandwidth and storage space in the cloud applications. Facing the demands, an efficient and secure plaintext-related chaotic image encryption scheme is proposed based on compressive sensing for achieving the compression and encryption simultaneously. In the proposed scheme, the internal keys for controlling the whole process of compression and encryption is first generated by plain image and initial key. Subsequently, discrete wavelets transform is used in order to convert the plain image to the coefficient matrix. After that, the permutation processing, which is controlled by the two-dimensional Sine improved Logistic iterative chaotic map (2D-SLIM), was done on the coefficient matrix in order to make the matrix energy dispersive. Furthermore, a plaintext related compressive sensing has been done utilizing a measurement matrix generated by 2D-SLIM. In order to make the cipher image lower correlation and distribute uniform, measurement results quantified the 0∼255 and the permutation and diffusion operation is done under the controlling by two-dimensional Logistic-Sine-coupling map (2D-LSCM). Finally, some common compression and security performance analysis methods are used to test our scheme. The test and comparison results shown in our proposed scheme have both excellent security and compression performance when compared with other recent works, thus ensuring the digital image application in the network.

To ensure the security and privacy of digital image when its transmitting online or storing in the cloud, we proposed a novel chaos based image encryption scheme by using randomly DNA encode and plaintext related permutation. In our scheme, we first randomly encode plain image into a nucleotide sequence under the control by the piecewise linear chaotic map(PWLCM). After that, the plaintext related permutation would be done under the control sequence which generated by hyper chaotic Lorenz system (HCLS). Next, we make diffusion processing with key DNA sequence which is generated by another PWLCM system and also encoded randomly. Finally, we decode DNA sequence into cipher image matrix. In addition, we used many common security analysis methods to test our scheme, and the result compared with other works. The tests and comparison results are shown that our proposed image cryptosystem has excellent security performance to ensure the digital image security on communication.

In Industry 5.0, there are increasing demands for group communication with low energy consumption and high communication efficiency from a great number of Internet of Things (IoT) devices. However, group communication is still exposed to various security risks. Although some cryptographic schemes have been devised to facilitate secure group communication, the existing schemes generally rely on a trust authority to periodically issue certificates and have led to various issues, such as failing to support anonymity and flexible key management, and cannot resist the single point of failure. Therefore, in this work, leveraging Chebyshev chaotic maps and blockchain, an anonymous authentication and key management scheme is proposed to provide secure and efficient group key generation and management for mutual authentication between communication entities. The scheme exploits the blockchain to save the key materials associated with IoT devices, thereby it ensures data privacy and provides a secure environment for communication. The scheme also employs the Chebyshev polynomial to generate a group key for the IoT devices within a group, and later the group members holding the same group key can use it for secure communication. The formal and informal security analysis demonstrates that the proposed scheme can meet the security and flexible key management requirements. The detailed performance analysis shows that the proposed scheme has acceptable computation and communication energy consumption and provides superior security in comparison with existing schemes.