Watermarking of Compressed and Encrypted JPEG Images

In this project, a robust watermarking can be added to the compressed and encrypted JPEG images. For applicative purpose digital asset management systems (DAMS) generally handles media data in a compressed and encrypted form. And sometimes it is necessary to watermark this compressed encrypted image items in the compressed-encrypted domain itself for tamper detection or ownership declaration or copyright management purpose. It is difficult to watermark these compressed encrypted streams as the compression process would have packed the information of raw media into a low number of bits and encryption would have randomized the compressed bit stream. Attempting to watermark such a randomized bit streams can cause a dramatic degradation of the media quality. Thus it is necessary to choose an encryption scheme that is both secure and will allow watermarking in a predictable manner in the compressed encrypted domain. In this project, a robust watermarking algorithm is proposed to watermark JPEG compressed and encrypted images. The encryption algorithm we propose to use is a stream cipher. While the proposed technique embeds watermark in the compressed-encrypted domain, the extraction of watermark can be done in the decrypted domain.