关键词: 公钥系统, 可逆数字水印, 混沌系统, 直方图, 峰值

Abstract: A reversible digital watermarking based on public key system was proposed to improve the security, transparency and embedding capacity. This technique shifted the pixels between the peak and zero in the histogram, extracted the characteristics of the original image, used the Boolean exclusive OR operator between the characteristics value and the watermark image processed with chaotic system, and finally embedded the value into the image with the public key. Verification process was the inverse process of the embedding. After the verification, the shifted pixels were recovered depending on the relationships of the peak and zero in the histogram, and the image was recovered. The public key system and chaotic system guarantee the system security. The shift between the peak and zero pixels ensured more embedded information, higher peak signal- to-noise ration, and authentication of all the pixels. The process was simulated with lots of images. The results show that the method is safer than others, can embed more information, and has more transparency.

Key words: public key system, reversible watermarking, chaotic system, histogram, peak value