Journal of Computer Science 4 (12): 999-1002, 2008 ISSN 1549-3636 © 2008 Science Publications Corresponding Author: Abdelfatah A. Yahya, Faculty of Science and Information Technology, Al-Zaytoonah University of Jordan, Queen Alia Airport Road, Amman 11733, Jordan 999 A Shuffle Image-Encryption Algorithm Abdelfatah A. Yahya and Ayman M. Abdalla Department of Computer Science, Al-Zaytoonah University of Jordan, Amman 11733, Jordan Abstract: Problem statement: Image encryption needs to be secure by resisting statistical attacks and other types of attacks. Approach: The new algorithm, call it the Shuffle Encryption Algorithm (SEA), applies nonlinear s-box byte substitution. Then, it performed a shuffling operation partially dependent on the input data and uses the given key. Results: SEA was implemented and tested with different data, mainly consisting of images. Results confirmed its security, shown through statistical analysis using histograms, correlation and covariance. Conclusion: New algorithm was suited for encrypting images and other types of data. Key words: Cryptography, image encryption, s-box, rijndael INTRODUCTION The study of cryptography has become increasingly important, as progressively more information is stored and transmitted in electronic form. This led to the creation of many encryption algorithms and standards. One of the most popular standards today is the Advanced Encryption Standard (AES), also known as Rijndael. This standard is the cipher of choice for many official and commercial organizations around the world and it is used in encrypting many forms of electronic data. A detailed explanation of the design of AES is available [5] . The AES uses byte substitution using a table called an s-box. More s-box construction methods were developed later [1,4] . AES may also be implemented efficiently on smart cards [9] . Some studies were made on image encryption using AES [2,7] and using matrix transformation [10,11] . The security of AES was demonstrated by its resistance to attacks when it was applied with ten or more rounds using a key of at least 128 bits [3,8,12-14] . Other encryption algorithms based on AES were also developed [6,12,13] . A new encryption algorithm is presented. The new algorithm, called the Shuffle Encryption Algorithm (SEA), uses a nonlinear byte-substitution step using an s-box and a shuffle operation. This new algorithm is reasonably secure, as shown by the implementation results. MATERIALS AND METHODS The new SEA algorithm starts with nonlinear byte substitution using a lookup table (s-box) and then it performs linear shuffling of the result. These two steps are performed for k rounds, where the key consists of k numbers, k≥1. The shuffling step is both key dependent and data dependent. Let the bytes of an (n×m)-byte image be numbered left to right, row by row, starting with number (j = 1) for the first byte of the first row and ending with number (j = nm) for the last byte of the last row. The encryption algorithm using SEA is as follows: Generate s-box For i = 1 to k fixBit = Key[i] D = Vector where D[j] is the value of bit (fixBit) of the j th byte of the current image S0 = Vector containing numbers of current image bytes (j) that have (D[j] = = 0) S1 = Vector containing numbers of current image bytes (j) that have (D[j] = = 1) Shuffle = Concatenation of S0 with S1 Substitute the bytes of the current image so that the new location of byte (j) is byte (Shuffle[j]) Substitute the bytes of the resulting image using the s-box table End For This algorithm takes an image (or another data item) and a key consisting of k numbers as input and it works as follows. First, an s-box substitution table is constructed to perform two transformations: multiplicative inverse and affine transformation. The algorithm takes k rounds, where k≥1. Each round takes