Performance Analysis of JPEG2000 Images In a Compressed and Encrypted Domain Using Three Different Watermarking Techniques

Digital Asset Management (DAM) systems generally involve the digital assets like images, graphics, logos, audio/video clips. These digital assets will contain some additional information and these files should be accessible only to the intended users. So these digital assets should be in a compressed and encrypted domain. The owner distributes the media to the consumers by multiple levels of distributors. Since the distributors are not the consumers they cannot have access to the original message. So before the owner distributes the message to the distributors, the message should be compressed and encrypted. Sometimes these compressed encrypted media items can be accessible to unwanted users so watermarking of these media items should be done. It is difficult to watermark such compressed encrypted streams since a small modification in the compressed and encrypted bit stream leads to degradation in the media quality. Thus we need to choose proper encryption algorithm which will allow secure watermarking in compressed-encrypted domain. The encryption algorithm used in this paper is stream cipher RC6. In this paper, we propose a robust watermark embedding technique for JPEG2000 compressed and encrypted images. The watermark embedding is done in the compressed encrypted domain, the extraction of watermark can be done either in decrypted domain or in encrypted domain. We investigate in detail the Peak Signal to Noise Ratio (PSNR) and the security of the proposed algorithm, using three watermarking schemes: Spread Spectrum (SS), Scalar Costa Scheme Quantization Index Modulation (SCS-QIM), and Rational Dither Modulation (RDM).