The Des Linear Cryptanalysis

American 20th century data encryption standard DES is so far usesbroadly, discusses one of most block cipher algorithms. In past severaldozens years, DES (Date Encryption Standard) the material encryptionstandard is continuously acting the strong character in the materialsecurity aspect, Widely is applied in aspects and so on trade, military,secret signaling and status authentication. Current attacked DES the mainmethod to have the linear cryptanalysis and the difference cryptanalysismethod and so on, this article has studied systematically to the DES linearcryptanalysis method. Inspects DES security intensity Through linearcryptanalysis method.This paper dissect DES algorithm realization process, Elaborated theDES S box characteristic, as well as sub-key production process; then thedissect linearity method of attack, and gave an example to simulate thelinear attack process, Has broken a code the part key ; has carried on thecomparison to the linear attack three different algorithms, has completedthe simulation process which the DES key attacked; Uses the central limittheorem, the normal distribution establishment statistics experimentalmodel in this foundation, and attacked the successful probability and thelinear attack complexity to the linearity has carried on the theoreticalanalysis.This simulation process provide not only one for studying in theory,but also application for cryptanalysis in practice, only then thoroughlydo a thorough research and the discussion to the linear attack law, canenable the block cipher which the future will design to resist the linearattack method attack.