The Research And Software Development Of Stream Ciphers Based On Quasigroups

Stream cipher system is an important branch of symmetric cipher system.Compared with block cipher,stream cipher has obvious advantages in hardware implementation and encryption speed.Therefore it is more than suitable to transfer big data and suitable to use under the limit of software and hardware.The cardinal points of early research on stream ciphers focus on nonlinear stream generator of linear feedback shift register stream,such as feedforward,combination and Clock control etc,and there are abundant research production on pseudorandom properties of these streams and some analytical respect on generator.Additionally there still are many stream cipher algorithms which have relatively mature research achievement,but because of lacking open relatively standards in the world,stream cipher is far less mature than block cipher.European NESSIE project start-up in 2000 and European stream cipher project eSTREAM start-up in 2004 greatly promote the development of stream cipher system design and analysis.A new generation of stream cipher algorithms which are winners in the European stream cipher project is a symbol of nonlinear driving and iteration becoming a main stream of stream cipher algorithm and they will become a main hotspot about analysis of stream cipher algorithm in the future.Combinatorial design theory in the combinatorial mathematics has more and more applications in the field of cryptography,error correcting code,computer science and network theory,and it provide basic theory for computer science and other applied science to deal with discrete structure.Quasigroup theory is a research field in the combinatorial design theory which is classical and has relatively more problems to be solved.Recently,Quasigroup theory has already developed fast in the cryptology applies,and it gives rise to many encryption algorithms,Hash function algorithms and Message authentication algorithms etc.Edon80 is a binary addition synchronization stream cipher code.It is one algorithm of candidates for eSTREAM project,and it's advantages are that it can be parallel and can be extend in largely besides it operates fast and requires low resource.But there are two defects in it.One of which is that it exists possibilities of small period in a little probability,another defect is that it can not resist secret key recovery assault.The two defects make it be abandoned in the last round of screening.This paper analysis the two defects of Edon80 and improve the algorithm of Edon80 to overcome these defects.Chains80 is another stream cipher based on Edon80.It remains the advantages of Edon80 which include hight parallelism,hight expansion and operate fast,and it overcomes the disadvantages of Edon80 which include short periods and no ability to resist secret key recovery assault.This paper will develop an encryption software system based on Chains80 by C++ language.The software has advantages of being able to operate parallel and of requiring low recourse.The development of this software includes interface design and function realization.In order to improve running speed in the process of encryption operation,the software use three technologies: parallel operation,thread and file map.Parallel operation is the advantage of Chains80.The theory of(sub)thread technology is dividing the document into parts and encrypting them simultaneously,so it speeds up operation speed.The software has four subthread,one of them is used to the design of progress bar.Another three subthreads and main thread are used to encryption operation.The technology of file map can read data from resource file directly,resulting in reducing IO operation in the computer,so it speeds up running speed largely.The software uses interactive interface and it uses message mapping technology to implement the function of draw selected file to edit box.Besides it also uses model dialog box and modeless dialog box technology.When it shows popup dialog,if the popup dialog can be edited but the main dialog can't be edited,and at this time this dialog is called model dialog box,and in the contrary,it is a modeless dialog box.The software uses modeless dialog box in the progress bar settings,but uses model dialog box in the password judgment and file selection.This chapter is organized as follows:(1)Chapter one is an introduction about the paper.It introduces the history of stream cipher development and the hot direction at present.(2)Chapter two describes the algorithm theory of Edon80,and analysis the defects of Edon80,and improves the algorithm based on Edon80.(3)Chapter three introduces the algorithm theory of Chains80 which base on algorithm theory of stream cipher of 3-Quasigroup;it analyses the difference between Chains80 and Edon80 and the advantages of Chains80.(4)Chapter four introduces design principle,algorithm program and each module function of this software which is developed based on Chains80.(5)Chapter five is the instruction of stream cipher system based on Chains80 under the interactive interface.