Application Of S-boxes In The Sequence Password

S-box first appeared in the Lucifer algorithm and became popular with the application of the DES. S-box is the only nonlinear component in many cryptosystem.T the strength of the S-box determines the strength of the whole cryptosystem, and its efficiency determines the confuse speed of the whole cryptosystem. Specially, the S-box with high strength plays a role in strengthening the scurity of the cipher with Feistel, SPN and IDEA.With the development of Cryptography, the S-boxes which only used for block cipher design originally have been gradually applied to the design of the stream cipher. Previous research on the S-boxes are concentrated on how to construct and design better S-boxes,and the better meet the S-box design criteria are:differential properties, nonlinearity,algebraic degree, distributionof term, diffuse criteria, Correlation Immunity and balancity. With the European eSTREAM (European Network of Excellence for Cryptology) project to rise, S-box for the first time and with a wide range be used in the design for stream ciphers, the studies that S-boxes applied in the Stream Cipher will be a new direction in the study of the Cryptography.This thesis focused the European NESSIE(New European Schemes for Signatures, Integrity, and Encryption) project and eSTREAM project, especially for the case of that to take advantage of block cipher components S-box structure stream cipher in the eSTREAM project. Introduced the definition of the S box and the cryptographic properties of it,stats its usages in eSTREAM project. Analyzed an academic paper "a new key stream generator design algorithm" which designed base on the S-box, some of the shortcomings and deficiencies of it were pointed out. According to the idea of using block cipher components S-box design stream ciphers and analysis on "a new key stream generator design algorithm", the algorithm of it has been improved. Given a improved sequence generation algorithm which based on the S-box and its analysis.