In the current time there is an important problem that is for a received linear or nonlinear binary sequence{z_(n)}how we can find the nonlinear feedback shift register and its linear equivalent which generate this se...In the current time there is an important problem that is for a received linear or nonlinear binary sequence{z_(n)}how we can find the nonlinear feedback shift register and its linear equivalent which generate this sequence.The linear orthogonal sequences,special M-Sequences,play a big role in these methods for solving this problem.In the current research trying give illuminations about the methods which are very useful for solving this problem under short sequences,and study these methods for finding the nonlinear feedback shift register of a multiplication sequence and its linear equivalent feedback shift register of a received multiplication binary sequence{z_(n)}where the multiplication on h degrees of a binary linear sequence{a_(n)},or finding the equivalent linear feedback shift register of{z_(n)},where the sequence{z_(n)}of the form M-sequence,and these methods are very effectively.We can extend these methods for the large sequences using programming and modern computers with large memory.展开更多
Based on analysis of the structure characteristics and implementation methods of some representative word oriented linear feedback shift registers （LFSRs） in several modem software oriented stream ciphers, this pape...Based on analysis of the structure characteristics and implementation methods of some representative word oriented linear feedback shift registers （LFSRs） in several modem software oriented stream ciphers, this paper firstly classifies the word oriented LFSRs into two classes： the machine instruction type and the arithmetic type. The similarities and differences between each type are illustrated by concrete examples. Then we give a detailed analysis about the word oriented LFSRs in each category from design structure, cryptographic properties and implementation issue aspects. Finally, some basic design criteria for modem word oriented LFSRs and suitable for software implementation are summarized.展开更多
An algorithm based on eigenanalysis technique and Walsh-Hadamard transform （WriT） is proposed. The algorithm contains two steps. Firstly, the received sequence is divided into temporal windows, and a covariance matr...An algorithm based on eigenanalysis technique and Walsh-Hadamard transform （WriT） is proposed. The algorithm contains two steps. Firstly, the received sequence is divided into temporal windows, and a covariance matrix is computed. The linear feedback shift register （LFSR） sequence is reconstructed from the first eigenvector of this matrix. Secondly, equations according to the recovered LFSR sequence are constructed, and the Walsh spectrum corresponding to the equations is computed. The feedback polynomial of LFSR is estimated from the Walsh spectrum. The validity of the algorithm is verified by the simulation result. Finally, case studies are presented to illustrate the performance of the blind reconstruction method.展开更多
This letter proposes algebraic attacks on two kinds of nonlinear filter generators with symmetric Boolean functions as the filter fimctions. Different fxom the classical algebraic attacks, the proposed attacks take th...This letter proposes algebraic attacks on two kinds of nonlinear filter generators with symmetric Boolean functions as the filter fimctions. Different fxom the classical algebraic attacks, the proposed attacks take the advantage of the combinational property of a linear feedback shift register （LFSR） and the symmetric Boolean function to obtain a tow-degree algebraic relation, and hence the complexities of the proposed attacks are independent of the algebraic immunity （AI） of the filter functions. It is shown that improper combining of the LFSR with the filter function can make the filter generator suffer from algebraic attacks. As a result, the bits of the LFSR must be selected properly to input the filter function with large AI in order to withstand the proposed algebraic attacks.展开更多
Random numbers play a crucial role in modern security schemes. Couple to the rapid development of cryptography, the strength of security protocols and encryption algorithms consumingly relies on the quality of random ...Random numbers play a crucial role in modern security schemes. Couple to the rapid development of cryptography, the strength of security protocols and encryption algorithms consumingly relies on the quality of random number. With simple architecture and faster speed, linear feedback shift register often is selected in many applications. However, the random sequence generated by LFSR can not meet the demand of unpredictability for secure mechanism. Genetic algorithm improves the linear property of LFSR and constructs a novel random sequence generator with longer period and complex architecture.展开更多
The linear complexity of a new kind of keystream sequences.FCSR sequences,is discussed by use of the properties of cyclotomic polynomials.Based on the results of C.Seo's,an upper bound and a lower bound on the li...The linear complexity of a new kind of keystream sequences.FCSR sequences,is discussed by use of the properties of cyclotomic polynomials.Based on the results of C.Seo's,an upper bound and a lower bound on the linear complexity of a significant kind of FCSR sequences—l-sequences are presented.展开更多
文摘In the current time there is an important problem that is for a received linear or nonlinear binary sequence{z_(n)}how we can find the nonlinear feedback shift register and its linear equivalent which generate this sequence.The linear orthogonal sequences,special M-Sequences,play a big role in these methods for solving this problem.In the current research trying give illuminations about the methods which are very useful for solving this problem under short sequences,and study these methods for finding the nonlinear feedback shift register of a multiplication sequence and its linear equivalent feedback shift register of a received multiplication binary sequence{z_(n)}where the multiplication on h degrees of a binary linear sequence{a_(n)},or finding the equivalent linear feedback shift register of{z_(n)},where the sequence{z_(n)}of the form M-sequence,and these methods are very effectively.We can extend these methods for the large sequences using programming and modern computers with large memory.
基金Supported by the National Basic Research Program of China (937 Program) (2007CB807902)the National High-Technology Research and Development Program of China (863 Program) (2006AA01Z425)the National Natural Science Foundation of China (60503011, 90704003)
文摘Based on analysis of the structure characteristics and implementation methods of some representative word oriented linear feedback shift registers （LFSRs） in several modem software oriented stream ciphers, this paper firstly classifies the word oriented LFSRs into two classes： the machine instruction type and the arithmetic type. The similarities and differences between each type are illustrated by concrete examples. Then we give a detailed analysis about the word oriented LFSRs in each category from design structure, cryptographic properties and implementation issue aspects. Finally, some basic design criteria for modem word oriented LFSRs and suitable for software implementation are summarized.
基金supported by the National Natural Science Foundation of China(61072120)
文摘An algorithm based on eigenanalysis technique and Walsh-Hadamard transform （WriT） is proposed. The algorithm contains two steps. Firstly, the received sequence is divided into temporal windows, and a covariance matrix is computed. The linear feedback shift register （LFSR） sequence is reconstructed from the first eigenvector of this matrix. Secondly, equations according to the recovered LFSR sequence are constructed, and the Walsh spectrum corresponding to the equations is computed. The feedback polynomial of LFSR is estimated from the Walsh spectrum. The validity of the algorithm is verified by the simulation result. Finally, case studies are presented to illustrate the performance of the blind reconstruction method.
基金Supported by the National Basic Research Program of China （No. 2007CB311201）, the National Natural Science Foundation of China （No.60833008 No.60803149）, and the Foundation of Guangxi Key Laboratory of Information and Communication （No.20902）.
文摘This letter proposes algebraic attacks on two kinds of nonlinear filter generators with symmetric Boolean functions as the filter fimctions. Different fxom the classical algebraic attacks, the proposed attacks take the advantage of the combinational property of a linear feedback shift register （LFSR） and the symmetric Boolean function to obtain a tow-degree algebraic relation, and hence the complexities of the proposed attacks are independent of the algebraic immunity （AI） of the filter functions. It is shown that improper combining of the LFSR with the filter function can make the filter generator suffer from algebraic attacks. As a result, the bits of the LFSR must be selected properly to input the filter function with large AI in order to withstand the proposed algebraic attacks.
基金Supported by the National Natural Science Foundation of China (60373087, 90104005 and 60473023)
文摘Random numbers play a crucial role in modern security schemes. Couple to the rapid development of cryptography, the strength of security protocols and encryption algorithms consumingly relies on the quality of random number. With simple architecture and faster speed, linear feedback shift register often is selected in many applications. However, the random sequence generated by LFSR can not meet the demand of unpredictability for secure mechanism. Genetic algorithm improves the linear property of LFSR and constructs a novel random sequence generator with longer period and complex architecture.
基金The work is supported by the Special Fund of National Excellently Doctoral Paper and HAIPURT.
文摘The linear complexity of a new kind of keystream sequences.FCSR sequences,is discussed by use of the properties of cyclotomic polynomials.Based on the results of C.Seo's,an upper bound and a lower bound on the linear complexity of a significant kind of FCSR sequences—l-sequences are presented.
