An Image Encryption Approach Using a Combination of Permutation Technique Followed by Encryption

Data encryption is widely used to ensure security in open networks such as the internet. Each type of data has its own features, therefore, different techniques should be used to protect confidential image data from unauthorized access. Most of the available encryption algorithms are used for text data, however, due to large data size and real time constrains, algorithms that are good for textual data may not be suitable for multimedia data. In most of the natural images the values of the neighboring pixels are strongly correlated. This means that the value of any given pixel can be reasonably predicted from the values of its neighbors. In this paper, we introduce a new permutation technique based on the combination of image permutation and a well known encryption algorithm called RijnDael. The original image was divided into 4 pixels x 4 pixels blocks, which were rearranged into a permuted image using a permutation process presented here, and then the generated image was encrypted using the RijnDael algorithm. The results showed that the correlation between image elements was significantly decreased by using the combination technique and higher entropy was achieved.