Robust watermarking of AES encrypted images for DRM systems

Digital image capturing, processing and distribution has showed a remarkable growth over recent years. This media content is sometimes distributed in encrypted format and watermarking of these media items for proof of ownership, media authentication needs to be carried out in encrypted domain to improve image security. Therefore it is sometimes necessary to embed watermark in encrypted media items for ownership declaration or copyright management purposes. DRM system is one such example where there is a challenge to watermark these encrypted data as the encryption would have randomized the incoming data. In this paper, a block cipher called AES-128 bit key encryption algorithm and DCT combined with DWT based watermarking algorithm to watermark the encrypted image were proposed which increases robustness of the watermark. These method embeds the binary watermark in encrypted image and decryption is done after extraction of watermark.