The need for information security has become urgent due to the constantly changing nature of the Internet and wireless communications, as well as the daily generation of enormous volumes of multimedia. In this paper, a 3-stage image cryptosystem is developed and proposed. A tan variation of the logistic map is utilized to carry out deoxyribonucleic acid (DNA) encoding in the first stage. For the second encryption stage, the numerical solution of the Lorenz differential equations and a linear descent algorithm are jointly employed to build a robust S-box. The logistic map in its original form is utilized in the third stage. Diffusion is guaranteed through the first and third encryption stages, while confusion is guaranteed through the application of the S-box in the second encryption stage. Carrying out both confusion- and diffusion-inducing stages results in encrypted images that are completely asymmetric to their original (plain) counterparts. An extensive numerical analysis is carried out and discussed, showcasing the robustness and efficacy of the proposed algorithm in terms of resistance to visual, statistical, entropy, differential, known plaint text and brute-force attacks. Average values for the computed metrics are: Information entropy of 7.99, MSE of 9704, PSNR of 8.3 dB, MAE of 80.8, NPCR of 99.6 and UACI of 33. The proposed algorithm is shown to exhibit low computational complexity, encrypting images at an average rate of 1.015 Mbps. Moreover, it possesses a large key space of 2372, and is demonstratd to successfully pass all the tests of the NIST SP 800 suite. In order to demonstrate the superior performance of the proposed algorithm, a comparison with competing image encryption schemes from the literature is also provided.

Due to the extensive demand for digital images across all fields, the security of multimedia data over insecure networks is a challenging task. The majority of the existing modern encryption schemes are merely developed that ensure the confidentiality of the image data. This manuscript presents a new image encryption scheme that ensures confidentiality, user authentications, and secure key sharing among the communicating parties. Initially, the users share a secret parameter using Diffie-Hellman over the elliptic curve and pass it through SHA-256. Afterwards, the proposed scheme uses the first 128-bits for the confidentiality of the data, while the remaining 128-bits are for authentication. In the encryption algorithm, the confusion module is achieved by affine power affine transformation. At the same time, the diffusion module is attained through highly nonlinear sequences, which are generated through the elliptic curve. Experimental testing and the latest available security tools are used to verify the effectiveness of the proposed algorithm. The simulation findings and the comparison of the proposed scheme with the existing image encryption techniques reveal that the suggested scheme offers a sufficient degree of security. Furthermore, the outcome of the simulation results divulges several advantages of the proposed scheme, including a large key space, resistance to differential attacks, high efficiency, and strong statistical performance.

In this manuscript, we propose an image encryption technique by using isomorphic elliptic curves which are proved to be effective against side-channel attacks and have efficient key size as compared to other public-key structures. The proposed technique counts on the Kobltiz method to convert plain images into elliptic curve points. These points are then mapped to the isomorphic curve and are the reason for diffusion in the ciphertext. Besides this diffusion mechanism, elliptic curve points are also involved in the construction of small substitution boxes for confusion. This proposed confusion and diffusion technique also provides quality security in response to well-known cryptographic attacks as established by the number of statistical results and security analysis.

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The mathematical operation of the Elliptic Curve over the prime finite field is wildly used for secure data communication as it provides high security while utilizing the same size as the secret key. This manuscript presents a novel approach the SPN (Substitution Permutation Network) for a new digital audio encryption scheme based on Mordell elliptic curve (MEC) over a finite prime field. The proposed scheme consists of a confusion and diffusion module. For the confusion module, the scheme initially generates 5 × 5 bijective S-boxes, which have never been applied in the present literature with good cryptographic properties. The generated S-box is then used parallel in the substitution module, which provides optimum confusion in the cipher data. For the diffusion property, the scheme generates pseudorandom number sequences used for block permutation and achieves the property of diffusion. The scheme has been thoroughly securitized against various attacks. The result shows the efficiency of the proposed algorithm over the existing schemes. In addition, the framework that is used to generate MEC points is based on the searching technique. Consequently, it significantly reduces the computational cost and enhances the scheme's performance compared to the schemes presented in the literature.

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