Securing Images using Bifid Cipher associated with Arnold Map.

This article presents a novel image encryption scheme combining a modified Bifid cipher and Arnold map within a substitution-permutation framework to enhance image data security. The traditional 2D-Bifid cipher is extended to handle color images by using a 16×16 key matrix covering pixel values from 0 to 255, while a block-based Arnold map method encrypts images of arbitrary sizes, including non-square dimensions. The scheme operates in two phases, each applying Bifid cipher-based substitution followed by Arnold map-based diffusion, with key sensitivity not only to exact keys but also to their precise orderings. Extensive simulations and analyses demonstrate the scheme's robustness against statistical and cryptanalytical attacks, including noise and cropping attacks, showing high randomness, negligible pixel correlation, strong differential characteristics, and a vast key space that resists brute force and common cryptanalytic attacks. Comparative studies indicate that this approach outperforms or matches related works in security, efficiency, and applicability to various image sizes, making it suitable for securing image data in fields such as medical imaging, military communication, and satellite networks.