An optical-based encryption and authentication algorithm for color and grayscale medical images

The continuous digitization of healthcare services makes them more targeted by security attackers that attempt to steal the patients' confidential records and hijack their healthcare rights. Consequently, many existing approaches were proposed to protect healthcare data and services. However, these current solutions lack efficiency, as indicated by the high number of security breaches in healthcare systems. Therefore, this research was motivated to introduce a more efficient algorithm that achieves several essential security requirements such as authentication, confidentiality, and integrity while preserving high resistance against a comprehensive set of different security threats. This proposed algorithm is a hybrid optical-based that utilizes effective hashing, steganography, and encryption techniques for the secure transmission of color or grayscale medical images, even over insecure channels. The input medical image is initially decomposed into three color components (red, green, and blue). Then, each one of these color components is forwarded to multiple sequential security stages. At the first security stage, the Discrete Wavelet Transform (DWT)-based compressive sensing technique is employed to compress the color components of the plaintext medical image to obtain the compressed image components. After that, the sigmoid function-based quantization process is applied to the compressed image components to generate the digital quantized image components. The digital pixels of these components will then be encrypted using Rubik's cube-based encryption algorithm to obtain the final ciphertext medical image. In parallel, to ensure the authentication and integrity of the transmitted medical image, the image phase component is extracted using the optical Double Random Phase Encoding (DRPE) technique. Then, it is quantized before concatenation with a secret key and forwarded to the SHA-256 hashing algorithm to generate the HMAC digest (Hash-based Message Authentication Code value). The HMAC digest is then embedded using Least Significant Bit (LSB)-based steganography within the final encrypted color medical image to increase its secrecy. The proposed algorithm was extensively evaluated using different quality and security assessment metrics to validate its robustness and efficiency against various channel noise and attacks. The obtained outcomes prove the higher performance of the proposed algorithm for secure medical image communication than other recent and related security algorithms in terms of all tested computational and security parameters. In addition, the obtained results confirm that the optical-based security techniques have superior efficiency & robustness and low complexity compared to the related traditional digital-based security techniques.