The Research Of Rijndael Algorithm For Document Encryption

With the rapid development of computer technology and communication technology, the safety storage, safety handing and safety transport of electronic document is becoming more and more important. One of the important means to protect the electronic document is the encryption. Messages can be stored and transported in the form of cipher text to achieve the purpose of security and secrecy.In this paper, it analyzes merits of the block cipher: short-cut, rapid and easily standardization. It elaborates the design security principle, iterative structure and the basis of parameter selection of block cipher. The paper emphasis studies a classical algorithm of block cipher—Rijndael algorithm, also proposes an optimization Rijndael algorithm for software encryption. The original round function with four steps can be simplified to two steps. The optimization algorithm uses look-up table instead of a series of complex operations in the finite field, and the feasibility of this algorithm can be proved in theory. Then, the paper gives a specific design scheme of document encryption system. According to the amount of data and fast speed of document encryption, comparing with many encryption algorithms, the paper selects optimized Rijndael algorithm as the core algorithm of document encryption system. Meanwhile, in this system, it analyzes the work mode of algorithm and proposes a secret key protection scheme for document encryption. Finally, in the document encryption system, both the standard Rijndael algorithm and optimized Rijndael algorithm were tested. The result of tests shows that the optimized Rijndael algorithm owns faster speed compared with the standard algorithm.