Research On Chaotic Block Cipher Algorithm Applied To Wireless Sensor Networks

We describes the basic characteristics and the special securerequirements of the wireless sensor network(WSN) in this paper,moreover, the existing research for encryption algorithms for wirelesssensor networks are introduced, and the advantages and disadvantages ofthem are analyzed and compared. In order to satisfy the specialrequirements, we designed a chaotic block cipher algorithm for wirelesssensor networks. The algorithm uses a chaos key generator whoseconstruction is based on integer tent maps to generate the key sequence,and the Feistel symmetric block cipher structure.Chaotic tent maps can generate a pseudo-random sequence which isuniform distributed. But, due to the limited computing power, thewireless sensor nodes cannot directly handle complex operations such asfloating point arithmetic and division. So the tent maps, which is definedin the real number field, cannot be directly used in the WSN nodes. Byturning the tent maps into integer field, we make it is possible to achievein the WSN nodes. In order to improve and optimize the security performance of the integer tent maps, we use the methods of extensionand two-way coupling with parallel iterations, which can increase thecomplexity and strengthened the confusion and diffusion properties of theinteger tent maps. Experiments are designed to analyze the secureproperties of the coupled extended integer tent maps, the results show thatthe model, which has excellent secure properties, is an ideal choice as thekey sequence generator.The encryption algorithm uses the Feistel symmetric encryptionstructure, and, in order to avoid the redundant bytes, which may causeunnecessary energy consumption,8bits length plaintext block is chosen.The algorithm contains4rounds Feistel encryption and bit confusionbefore and after the Feistel structure. Experiments are taken to analyzethe nonlinear diffusion property and speed of the algorithm we designed,and for comparison, the same analysis is taken with the similar algorithm.The results show that the algorithm we designed meets the requirementsof nonlinear diffusion and has obvious advantages in securityperformance and operation speed.Design simulation experiments to verify the realization of thecryptographic algorithm. TOSSIM, a simulation tool, which is containedby TinyOS operating system(ver.1.1.0), is used in the experiment. Theprogram which is written by nesC language can achieve the encryptionand decryption well in the simulation experiment, that means the cryptographic algorithm we designed can be realized in wireless sensornetworks.