Research On Chaotic Block Cipher Based On Dynamic Rounds

To ensure the information security of resource-constrained devices such as smart card,radio frequency identification,and wireless sensor network has become a scientific issue that has attracted much attention in the field of cryptography.In order to better achieve the effective balance between security and efficiency of cryptographic performance,the chaotic block cipher based on dynamic rounds is studied in this paper.The main research contents are as follows:In view of the dynamic characteristics degradation of the chaotic system caused by the finite operation precision,the influence laws of quantization method and parameter setting on the digital chaotic characteristics are obtained through statistical test and analysis,and the compensation methods of cascading and disturbance are used to construct the digital chaotic models with dynamic characteristics significantly enhanced,so as to better meet the application requirements of the chaotic cryptographic component and algorithm design.Aiming at the local periodic phenomenon of the digital chaotic sequence is easily to cause weak keys,DNA encoding and genetic algorithm are introduced into the generation and expansion of chaotic keys respectively.DNA dynamic decision encoding rule and genetic iterative optimization mechanism are designed according to enhancing randomness and reducing correlation,which can effectively reduce the local imbalance of digital chaotic sequence with only a small computational cost,thus improving the security performance of the key.In order to solve the key problem of how to extract the element values of S-box based on chaos,one is to use the nonlinearity and randomness of digital cascaded chaotic iteration to traversal screening dynamically,and the other is to use fireworks algorithm to search for optimal values in the solution space of Lorenz chaos.Bothschemes can not only alleviate the large dependence of chaotic S-box on chaotic system it used,but also improve the construction efficiency while enhancing the confusion characteristics.According to the fact that increasing the number of encrypted rounds in traditional block ciphers will improve the security of ciphers,but too many encrypted rounds will affect the efficiency of ciphers,a dynamic rounds chaotic block cipher is proposed.The cipher enhances the anti-attack ability through the dynamic change of encrypted rounds,so that the security performance of large fixed rounds encryption can be achieved by dynamic rounds iteration in a small interval,thereby achieving the purpose of reducing resource overhead.For the traditional block cipher,the same encryption process is adopted for all plaintext information,which can easily lead to information leakage and deciphering due to insufficient security of encryption of important information,and unnecessary computational burden and resource consumption caused by the excessive security of encryption of non-important information.In response to the above problems,a dynamic rounds chaotic block cipher based on abstract extraction algorithm and suitable for online text encryption is proposed.The abstract extraction algorithm based on keywords is used to realize entity annotation of important information in the text plaintext,and a small amount of important information marked and a large amount of non-important information unmarked are respectively performed dynamic rounds encryption in the larger and smaller intervals.The cipher can achieve effective balance between security performance and resource consumption by implementing different levels of dynamic encryption for different information,which has certain theoretical significance and application value for ensuring information security of resource-constrained devices.