Enhanced Dual-Layer Image Encryption with DWT-DCT-SVD Hybrid Approach

Abstract

In the evolving landscape of telemedicine, ensuring the security of medical images has become increasingly critical. This paper introduces an advanced hybrid watermarking technique that integrates Discrete Wavelet Transform (DWT), Discrete Cosine Transform (DCT), and Singular Value Decomposition (SVD) using double encryption to safeguard medical images. The proposed methodology involves several steps: pre-processing medical images and watermarks, applying multiple levels of DWT decomposition, converting sub-bands to the frequency domain using DCT, and embedding the watermark into the singular values of DCT coefficients with SVD. The watermark is secured using circular and chaotic encryption techniques before embedding. The method's robustness, imperceptibility, and security were evaluated using a dataset of 100 medical images, each with a resolution of 512x512 pixels. Key performance metrics included Structural Similarity Index (SSIM), Peak Signal-to-Noise Ratio (PSNR), Mean Squared Error (MSE), and Normalized Correlation (NC). Experimental results demonstrated high PSNR values (35.2 dB to 38.4 dB), indicating minimal distortion and excellent image quality. SSIM values between 0.92 and 0.96 highlighted the preservation of structural integrity, while MSE values ranged from 11.0 to 15.8, reflecting low distortion. NC values close to 1 indicated strong robustness, ensuring the watermark closely matched the original even after various image processing attacks. This hybrid method offers a robust solution for secure medical image watermarking, balancing effective embedding with image quality preservation. The integration of DWT, DCT, SVD, and double encryption enhances security and resilience, making it highly suitable for telemedicine applications.