Region of interest-based medical image encryption technique based on chaotic S-boxes

Abstract

Block cipher has been one of the most reliable options by which data security is achieved. The strength of block cipher against various attacks is purely dependent on its confusion property, which is gained through the S-Boxes. In recent years, S-Boxes based on chaotic maps have become popular due to their favorable characteristics for cryptography. However, vulnerabilities have been discovered in these constructions, leading to concerns about their reliability. In this research, we first generate dynamic S-Boxes, and then based on the newly generated S-Boxes, a ROI-based medical image encryption scheme is proposed to address the challenges posed by the large size of DICOM images. Rather than encrypting the entire DICOM image, proposed encryption scheme only encrypts the ROI part where the relevant information is present, while leaving the black background unencrypted. This approach reduces the size of the encrypted data and improves the efficiency of the encryption process, while maintaining the privacy and confidentiality of sensitive medical data. The proposed ROI-based medical image encryption scheme is evaluated using standard performance metrics, including encryption speed, image quality tests, correlation-coefficient analysis, randomness of encrypted images, key sensitivity analysis, encryption sensitivity analysis, decryption sensitivity analysis, and resistance against common attacks such as differential and linear attacks. The proposed dynamic S-Box construction technique is evaluated using standard S-Box criteria, which include nonlinearity score, bit independence criterion, strict avalanche criteria, linear approximation probability, and differential approximation probability. Results demonstrate that the proposed technique gains high levels of encryption efficiency and security, making it a fast solution for secure medical image transmission in real-world applications.