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.
               
               
               
               Abstract
               
               
               
                  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.