Context-based watermarking cum chaotic encryption for medical images in telemedicine applications

In this paper, we propose a security system for secure transmission of medical images in telemedicine applications. The system couples an IWT-LSB watermarking and an encryption based on random permutation and chaos, to ensure confidentiality, integrity, authentication and nonrepudiation of medical images. We use IWT due to the sensitive nature of medical images and the need to retain diagnostic quality after image reconstruction. During the watermarking phase, the medical image is decomposed into wavelet sub-bands. Electronic patient record and extracted context information are then embedded in the least significant bits of the detail sub-band (host) coefficients. During encryption, the reconstructed watermarked medical image is randomly permuted and the permuted pixels diffused with a chaotic key stream to produce the cipher watermarked image. Experimental results and analyzes show that the system provides sufficient security against various forms of attacks. Furthermore, we propose a security architecture for the system.