Biclique Cryptanalysis On Lightweight Block Ciphers

With the vigorous development of Internet of Things in recent years,Internet of Things technology covers all aspects of our life.Its core technologies include radio frequency identification,wireless sensing,embedded systems,etc.The corresponding operating environments are mostly micro-computing devices or small chips and other devices.Due to the limited computing capacity and small physical area of these devices,the traditional block cipher algorithm cannot meet its operating conditions in the process of ensuring its security.Therefore,lightweight block cipher algorithm is needed to ensure the security of information transmission on Internet of Things devices.The algorithm structure of lightweight block cipher is relatively simple and requires fewer gates to implement,so it has no high requirements on the operating environment.Lightweight block cipher algorithm meets the security requirements of resource-limited devices,making it widely used in Internet of Things devices.Therefore,it is especially important to study the security of lightweight block cipher algorithm.This is not only to optimize the algorithm itself and ensure the data security in the operating environment,but also to contribute to the development of lightweight block cipher algorithm in the field of Internet of Things.This thesis first introduces the development status,lightweight concept and corresponding standards of block cipher at home and abroad,and then introduces some concepts of block cipher,including its mathematical model,overall structure,analysis method and security index.Next,the Biclique cryptanalysis method used in this thesis is described,including how to construct Biclique structure and how to use Biclique structure for specific analysis,and the analysis details and calculation method of its complexity are given.Then,it is the main work of this thesis,using Biclique cryptanalysis method to analyze the security of two lightweight block cipher algorithms,and the details are as follows:First,the Biclique cryptanalysis is carried out on the 96-key length version of the lightweight block cipher KLEIN algorithm,namely KLEIN-96.A 4-round 8-dimensional Biclique structure covering the 1st to 4th rounds in its plaintext direction is constructed firstly,and some bytes of its 10th round are selected as the intermediate variables,and then all the 20rounds are precomputed,matched and recomputed to realize the full-round Biclique cryptanalysis of KLEIN-96.The time complexity,the data complexity and the storage complexity are 2^95.06,2⁶⁴ and 2⁸ respectively.Secondly,the Biclique cryptanalysis is carried out on KLEIN-80,which is the 80-key-length version of the lightweight block cipher algorithm KLEIN.A 3-round 8-dimensional Biclique structure covering the 1st to 3rd rounds in its plaintext direction is constructed firstly,and some bytes of its 9th round are selected as intermediate variables,and then all the 16 rounds are precomputed,matched and recomputed,thus realizing the full-round Biclique cryptanalysis of KLEIN-80.The time complexity,the data complexity and the storage complexity are 2^78.99,2⁴⁰ and 2⁸ respectively.Then,the Biclique structure is extended backwards to construct a 4-round 8-dimensional Biclique structure covering the 1st to 4th rounds in the plaintext direction.Based on this,the analysis results are optimized,and the time complexity is reduced to 2^78.85,the data complexity and the storage complexity are2⁶⁴ and 2⁸ respectively.Third,the 128-key length version of the lightweight block cipher algorithm LED,namely LED-128,is analyzed by Biclique cryptanalysis method.A 12-round 8-dimensional Biclique structure covering the 37th to 48th rounds in the ciphertext direction is constructed firstly,and some bytes of its 18th round are selected as the intermediate variable,and all 48 rounds are precomputed,matched and recomputed to realize the full-round Biclique cryptanalysis of LED-128.The time complexity,the data complexity and the storage complexity are2^127.23,2⁶⁴ and 2⁸ respectively.At the end of this thesis,the full text is summarized,the development and prospect of Biclique cryptanalysis method are described and discussed in combination with the research results of this thesis.Meanwhile,the improved method is proposed,and the possible development direction of Biclique cryptanalysis method in the future is discussed.