Abdelkader Ouda and Mahmoud R. El-Sakka, "A Practical Version of Wong's Watermarking Technique", IEEE International Conference on Image Processing, ICIP'2004, pp. 2615 - 2618, October 2004, Suntec City, Singapore.
In this paper, we study the security of Wong's technique. It is shown that the technique is vulnerable to cryptographer's attacks. This is due to the use of short keys within the public-key cryptosystem. Short keys are used in Wong's technique to make the watermark small enough to fit in an image block. This paper proposes an elegant solution that helps Wong's technique to be practically implemented. A new method of applying the cryptographic hash function is utilized. This method makes the image blocks able to hold longer and secure watermarks while providing similar level of the localization accuracy. The experimental results show that the proposed solution carries Wong's technique from a cryptographically vulnerable system to a secure and practical one.