A secure image encryption algorithm combining random scrambling, interpolated radon-based diffusion and a novel one-dimensional chaotic map

In this paper, we propose a novel and secure image encryption algorithm that integrates interpolation in the Radon domain, random scrambling, and a newly designed Improved Delta Sine-Cosine (IDSC) chaotic map. Unlike previous studies, this work introduces image interpolation in the Radon domain, addressing the dimensional mismatch issue that arises after Radon transform and enabling standardised image sizes for effective encryption. To resolve this issue, we use interpolation in the Radon domain. The proposed scheme begins by applying the Radon transform to the input image, followed by spline interpolation to resize the transformed image to a fixed dimension of 256× 256. A two-level random scrambling strategy is then employed: first by block-level shuffling and then intra-block pixel scrambling, enhancing confusion. The IDSC chaotic map, with superior chaotic behaviour across a wide parameter range, is utilised for diffusion, while the Arnold map (AM) introduces additional scrambling to improve security. Extensive experimental results validate the proposed method’s robustness, demonstrating high key sensitivity, resistance to statistical and differential attacks, and strong encryption performance in terms of Number of pixels changing rate (NPCR), Unified average changing intensity (UACI), histogram, Peak signal to noise ratio (PSNR), Mean square error (MSE), Entropy Analysis, Chi-square test, Performance Analysis and Correlation coefficients (CC). This work provides a significant advancement by combining Radon-domain interpolation with a highly effective chaotic map, making it suitable for the secure transmission of sensitive image data.