Encoded Password In Information Security And Reliability Of Information Theory And Technology,

We discuss the theory and technology of coding and cryptology in the study of information security and information reliability in the disseration. Some valuable theoretic results are presented, most of these results are published on the important journey of china, parts of these results are used in some application system.In the design and analysis of error-correcting codes, we obtain the following results. First, considering the construction characteristic of Reed-Solomon code, we present a kind of new construction method for linear codes by using the factorization properties of cyclotomic polynomials on finite fields. We give the value of the code-length n and dimension k , and the lower bound of the minimal distances of the new linear code under some particular condition. The new linear code have the following characteristics: (l)The new code is the generalization of Reed-Solomon code and the linear code constructed by Chaoping Xing and San Ling in 2000; (2)Compared with Brouwer'table of the best known codes, we find more new codes, there are at least 100 new codes under two-dimension cases. Second, combining with the construction principle of Geometry-Goppa codes, we present a kind of new algebraic-geometry code by using the properties of algebraic curves on finite fields. We determine the value of the code-length n and dimension k , and the lower bound of the minimal distances of the new algebraic-geometry code. The new algebraic-geometry code have the following characteristics: (l)The new code is the generalization of Geometry-Goppa codes and the algebraic-geometry code constructed by Chaoping Xing and San Ling in 2000 (2)Compared with Brouwer'table of the best known codes, we find more new codes, there are at least 60 new codes under two-dimension cases. At last, By using the factorization properties of cyclotomic polynmials on finite fields and the construction characteristic of cyclic codes, we present the relation of the period distribution of cyclic codes and the period distribution of their dual codes, establish the explicit formula for the number of the codewords without inner-period of the cyclic codes and their dual codes, find the method for computing the dimension and the period distribution of narrow-sense primitive BCH codes,and study the inverse question of period distribution of cyclic codes.In the design and analysis of sequence cipher, we obtain the following results. First, we give the trace representation of primitive sequences and their corresponding highest lever sequences on Galois ring by using the trace function theory and the characteristic of lever factorization, and determine the correlation function linear complexity and element distribution of the highest lever sequences of primitive sequences on Galois ring GR(4, m). Second, we discuss the correlation properties and the Hamming correlation properties of a number of trace function generation sequences by using systematic ways. We calculate the correlation function of generalized trace function sequences which include No sequences> Kasami sequences and Kumar-Moreno sequences, and we also calculate the Hamming correlation function of No sequences^ Kasami sequences and Kumar-Moreno sequences. At last, we degine the frequency-hopping sequences with optimal Hamming correlation properties.In the design and analysis of block cipher, considering the noncontinuity ofencryption and decryption of Advanced Encryption Standard - Rijndael algorithm and the arbitrariness of the choice of polynomialm(x), we change the modular polynomial and the polynomials used in process of encryption and decryption, which the encryption polynomial and the decryption polynomial are the same polynomials in our choices. The new algorithm have more continuity. Considering the difference-resisting capacity of power function in classic S-box , we substitute the inverse function by better power function. We prove that these change do not influence the difference resisting capacity from the theory. Compared with the primary algorithm, the transmuta...