The Application Research Of Advanced Encryption Standard And Short Block Encryption Technology

AES/Rijndael algorithm is the Advanced Encryption Standard ofAmerica that is finalized to encrypt the sensitive data in 2000 has becomethe international standard in commerce field. The cryptanalysis andapplication study of AES are becoming more and more importance. Inpractical life, short-block encryption technology is widely applied, suchas pre-payment code-meter. It is necessary to study the key problems inshort block encryption and its application for pre-payment code-meterindustry, which is of great significance to the development of the nationaleconomy.AES/Rijndael algorithm is investigated in this thesis. Researchershave focused on developing the basic principle and design rule ofRijndael algorithm, the algebraic property of S-box, integral attack andalgebraic attack. Several methods of power analysis are compared andstudied. And the short-block encryption algorithm based on AES isdesigned and pre-payment code-meter communications is successfullyrealized. The key contributions follow below.(1) The algebraic expression of S-box is studied, the algebraicexpression with 9 items of S-box and the algebraic expression ofInvS-box with 255 items are given; it is pointed out that the periods ofaffined transformation is 4 and periods of iterative-output is less than 88;an improved method of S-box is proposed, and the new S-box have betteralgebraic properties in strict avalanche criterion, algebraic expression,affined transformation periods and iterative-output periods.(2) Integral attack and algebraic attack of Rijndael are analyzed, theSquare-5 attack and Square-6 attack are studied. Thus it draws theconclusion that the attack complexity of Square attack exceeds exhaustedsearch with encryption round increases. Square attack,conjoint-denominator expression of Rijndael, AES embedded in BES andXSL attack would fail against Rijndael by far. So Rijndael is the safest block cipher.(3) Power analysis of Rijndael is carded through. It is discoveredthat the best component of power analysis is nonlinear function. There issome ghost peak phenomena in DPA. There are more state bits in powerstatistic analysis (viz. high order DPA). The phenomena of ghost peakare less obvious. The effect of CPA analysis is better than DPA's. Thepower analysis method based on Walsh spectral is proposed, and therelation between power analysis and nonlinear degree is presented. Theconclusion goes that it is impossible to design a S-box that can resist inan optimal way to linear, differential and DPA attacks.(4) The decimal short-block encryption algorithm based on AESused in practical application with the block size 6, 8, 12, 16, 32 bits isdesigned in the thesis. The main characteristic of this algorithm is that itis a safe short-block encryption algorithm and the cipher has the samesize of the corresponding plaintext, so the algorithm can meet the specialrequirement of special industry, for example, the secret communication ofpre-payment code-meter industry.(5) Encryption communication mode of pre-payment code-meter isproposed, models of key allocation and dynamic key creation in systemare established, experiments and simulations of pre-payment code-meterare carried through, Square attack against short-block encryptionalgorithm is executed, tests of short-block encryption system are alsocarried through, and all the performances meet the practical applications.