Abstract
Very well evolved, information technology made so easy the transfer of all types of data over public channels. For this reason, ensuring data security is certainly a necessary requirement. Scrambling data is one solution to hide information from non authorized users. Presenting matrix content, image scrambling can be made by only adding a mask to the real content. A user, having the appropriate mask, can recognize the image content by only subtracting it. Chaotic function is recently used for image encryption. In this paper, an algorithm of image scrambling based on three logistic chaotic functions is proposed. Defined by its initial condition and parameter, each chaotic function will generate a random signal. The set of initial conditions and parameters is the encryption key. The performance of this technique is ensured for two great reasons. First, using masks on the image makes unintelligible its content. Second, using three successive encryption processes makes so difficult attacks. This point reflects, in one hand, a sufficient key length to resist to brute force attack. In the other hand, it reflects the random aspect of the pixel distribution in the scrambled image. That means, the randomness in one mask minimizes the correlations really existent between neighboring pixels. That makes our proposed approach resistant to known attacks and suitable for applications requiring secure data transfer such as medical image exchanged between doctors.