Comparative analysis of digital watermarking scheme using enhanced playfair cipher in DCT & DWT

During past few decades, communication over internet increased to transfer digital data across worldwide. The development of communication media over untrusted network bring lot of challenges for the developers. The algorithms and techniques should be robust, complex, and secure as well as ease of use and implementation in order to secure digital content over from potential risk and threats. In this paper, we have compared new encryption techniques as a preprocessing step for digital watermarking in Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) using the basics of playfair cipher. The proposed preprocessing step is implemented in different transform domain techniques to find the robust and secure way to embed ownership details in a cover media. The watermark image is encrypted using modified playfair cipher to form encrypted image which is further hidden in host media using DCT and DWT. The comparisons between different approaches are analyzed with the encrypted watermark information. The results and analysis show the robustness and security of these algorithms.