Improved image security scheme using combination of image encryption and reversible watermarking

In recent times, with the significant development of the internet, users have more opportunities to use multimedia contents. As a result, security of digital information has become a big problem. Reversible watermarking and cryptography has been regarded as an adequate solution to protect the digital data from illegal access. In this paper, a novel combination of reversible watermarking and image encryption technique based on the discrete cosine transform and scrambling technique is presented. Firstly, the plain image is encrypted by scrambling technique. Then, a lossless digital watermark is embedded in the encrypted image by a discrete cosine transform. Thus an encrypted image with watermark embedded in it is obtained. Finally, the original image can be recovered by the reverse process. Experimental results show that the proposed technique possesses high security and is able to withstand a variety of signal processing attacks.