Research On Guess And Determine Attack Of Stream Cipher And Its Application

Modern cryptography can be divided into symmetric cryptography and asymmetric?public key?cryptography.Symmetric ciphers are further divided into block ciphers,stream ciphers,hash algorithms,and so on.Stream cipher is mainly used for encrypting a single bit or word.The advantage is that the encryption and decryption speed is faster,and many of them are hardware-oriented.Stream cipher is wildly applied in military,wireless network,Bluetooth,mobile phone communication,RFID?Radio Frequency Identification?and other application scenarios.Cryptographic analysis technology has always been one of the core issues of cryptography.For the main analysis methods of stream ciphers,it is essentially possible to stipulate to solving a large system of equations.Guessing and determine attack is an important algebraic analysis method of stream cipher,by guessing some internal state bits of the algorithm,combined with key stream bits,etc.,to obtain a linear equation about the internal state of the algorithm,or a low nonlinearity equation.Then,solving the equations and obtaining the internal state of the algorithm.This method has a great influence on the design and analysis of stream cipher.In This paper,we mainly studied the guess and determin attack of three classical stream cipher algorithms,Grain v1,ACORN and LILI-128.Through the analysis of the internal functions of the algorithms,combined with other classical algebraic analysis methods,we gave the corresponding guessing and attack analysis.The main research results and innovations are as follows:?1?We studied the K-normality of the state update function of Grain v1 under given constraints.By analyzing the sampling resistance,combined with TMDTO?Time-Memory-Data-Trade-Off?,The guess and determine path of Grain-v1 is given.Compared with the TMDTO attack proposed by Bj?rstad et al.,our attack reduced online time by 2²⁶ and the precomputation complexity is reduced by 2^6.5,with a small increase in required key stream data and storage space.?2?We studied the nature of the guess and determine of the internal state feedback function of ACORN algorithm.Combined with the linear approximation equation of the8)?65?function in ACORN and its corresponding probability.We used the mathematical software Maple and solved the integer linear problem.And found the best guess and determine scheme The time complexity required to recover the 293 bits of internal state is 2¹⁵⁷.?3?We studied the relationship between the clock control structure of the LILI-128algorithm and the linear shift register of the data generator structure.Combined with the time-memory-data trade-off attack,a guess and determine attack of LILI-128 was proposed.We also analysised the selection of different parameters of TMDTO.Finally,compared with algebraic attack and related attack,our attack is the optimal attack,and the probability of success is 0.98 under certain parameters.