Research And Implementation Of Encryption Algorithm Using Layered Cellular Automata

As the explosive growth of information and communication technology and its wide applications today,information security has become indispensable and crucial.In the exploration of the autonomous techniques of cryptography,which is the kernel technique of information security,cellular automata has unique superiority in cryptography owing to its inherent features,such as simple structure,local interaction,high parallel information processing architecture and its complicated dynamic properties;and hence has the very important theory significance and the widespread application prospect.Focus on the applications of cellular automata in different fields of cryptography and on the basis of studying the theories of cellular automata and analyzing some existing cellular automata based encryption algorithms,this paper discusses the methods of layered cellular automata and reversible cellular automata based block encryption algorithms and public key encryption algorithms.The main contributions of this paper are as follows:1.After analyzing an existed block encryption algorithm based on layered and reversible cellular automata,it's found that the key structure of this algorithm is too simple,and the diffusion is barely satisfactory.Focus on these questions,a new block encryption algorithm using layered and reversible cellular automata is proposed.This algorithm enhances the interaction between different layers by using half-shift transformation not only in each layer,but also between adjacent layers,besides a random shift transformation is also employed,and hence shows more complex behavior.The simulation results show that this algorithm effectively improves the sensitivity of the ciphertext to plaintext and key,and therefore has a good diffusion and confusion effects.2.Considering that there are few one-dimensional reversible cellular automata,a method of constructing reversible cellular automata is proposed,and then,a reverse iteration encryption algorithm based on reversible cellular automata is constructed.This algorithm takes full advantage of the layered structure of the layered cellular automata,employs pseudo random sequence and XOR operations between different layers,and encrypts the plaintext backward and decrypt forward.The simulation results show that this algorithm has good diffusion and confusion effects,and the ciphertext is indistinguishable from the random sequences,which ensure that this encryption algorithm can against the statistical,linear and differential analysis attacks.3.Based on the analysis of the relationship between the image data structure and 8-layer cellular automata,a new image encryption algorithm using layered cellular automata is proposed.This algorithm is an extension and application of the reverse iteration encryption algorithm,also apply pseudo random sequence and random numbers,some improvements that random evolution on the random sequence is performed and the crossover operation between different layers is controlled by these random numbers,which resulted in the pixel randomly distributed in the encrypted image.Analysis and experiment results show that the encrypted images possess uniformly distributed pixel values and a low correlation between adjacent pixels,and also sensitivity to the key and plain image.Moreover,the key space of this algorithm is big enough.In conclusion,this image encryption algorithm is secure and has excellent performance.4.On the base of studying an existed public key encryption algorithm based on reversible cellular automata,a new neighborhood structure by means of layered cellular automata is defined,and then a novel layered cellular automata based public key encryption algorithm is proposed.This algorithm is proved to be indistinguishably secure against the chosen-plaintext attack by the aid of provable security theory,which make up for the shortcomings of the other cellular automata based public key encryption schemes.Besides,it can be improved to be secure against the chosen-ciphertext attack with the help of the random oracle.The key space analysis and simulation results show that this algorithm is more efficient when compared to the RSA-1024 encryption algorithm.5.According to the above public key encryption algorithm,a digital signature algorithm based on layered cellular automata is designed,which filled up the gap of applying cellular automata to design a digital signature scheme.Using some reversible one-dimensional transition rules to sign,which are kept as the private key,and the generated two-dimensional rules are kept as the public key and used to verify the signature.This algorithm is a random algorithm,since the states set,the neighborhood radius of the two-dimensional cellular automata and the number of the one-dimensional cellular automata are all not appointed,they are changed along with the actual applications.Based on the hardness of the two-dimensional cellular automata reversibility problem,this signature algorithm can be proved that it is existential unforgeability against adaptive chosen messages attack in the random oracle.