Now a days due to thedevelopment of technology more information are sharing in the form of image. Inorder to secure the image from an unauthorized person and accessing of privateinformation is becoming a serious challenge in the digital world. Hiding oftext by Advanced Encryption Standard (AES) and Data Encryption Standard (DES), those methods due to highcorrelation they are not suitable for multimedia infromation. Encryption is aprocess which uses finite set of instruction called an algorithm to convertoriginal image to an encrypted form. Cryptographic algorithm requires a key toencrypt (or) decrypt the data. Thecolor image is taken and divided it into red, green and blue components. Thethree-dimensional Arnold mapping is repeated to confuse the relations betweenpixels and six random sequences which are employed to replace the rows andcolumns of each color component.
The one-dimensional Logistic map is used to initializecellular automata. A one-dimensional non-uniform Cellular Automata (CA) with the rotationalboundary condition is used to create an image key which has a uniformdistribution of random numbers. Cellular Automata has a simple structure,random performance and complex behavior, and it is easy for hardware/softwareimplementations. In this proposed scheme hyper-chaotic Chen system is used toselect image key values to encrypt each components of color image. Chaotic 3Dcat map has larger key space and good chaotic behavior.
Logistic map has asimple structure and is easy to implement. Since hyper chaotic functions havelarger key space, they are more resistant against attacks. A one-dimensionalnon-uniform cellular automata which is initialized using logistic map is used.
Also, the selection of CA rules is performed randomly using this chaotic mapwhich results in robustness of the resulting key. Pixels permutation isperformed using chaotic map which results in the correlation reduction betweenpixels. The image encryption scheme is performed by doing of XOR operation withpermuted RGB image and image key produced by non uniform CA.
Therefore, theapproach is robust against differential attacks. The size of key space isflexible and can be extended based on newconditions. Using Chen hyper-chaotic function, a value is selected randomlyfrom the image key for the purpose of encryption.
The encrypted image isdecrypted in reverse process by using same arnold cat map algorithm with sameimage key which is generate from non uniform cellular automata. 2