The Research Of An Improved RC4 Algorithm For QR Code Encryption

With the rapid development of internet technologies, two dimensional barcode has been used in our society because of its high reliability and large amounts of information, the common two dimensional barcodes are PDF417、Code49、Data Matrix and QR code and QR code is the most widely used one.QR code, known as quick respond code, has the advantages of fast recognition, diverse coding modes and omnibearing recognition, which made rapid use of QR code and also bring the problem of security at the same time. In one word, the technology of the information encryption for QR code is required to be improved.Based on the existing research technologies, we choose the proper algorithm and mainly concentrate on the following works:1) We propose an improved RC4 algorithm based on the algorithm attack. By increasing the error detection stage we resist the attack of fault induction. Chaos algorithm has been introduced to improve the randomness of pseudo-random sequence in RC4 algorithm. Finally we validate the pseudo randomness of improved RC4 algorithm by using ideal random sequence of the international standards and discrete serial correlation test, to prove the effectively randomness of the improved RC4 algorithm.2) The information, which is being encoded into QR code graphic, is encrypted by using improved RC4 algorithm. Matrix graphic to be masked has been generated according to QR code encoding rules.3) Based on the characteristics of the interaction between particles of Ising model, we propose a double encryption for QR code matrix graphic to be masked. Let the QR code and the matrix which is the same size of QR code execute XOR operating and process the graphic to be masked. The generated QR code graphic is the graphic to be double encrypted.The innovations of the proposed algorithm are mainly as follows: Firstly, we propose two aspects of improvement for RC4 algorithm, one is to resist the algorithm attack of RC4 and the other is to improve the drawbacks of the feature of weak keys for algorithm and the randomness of the pseudo random sequence. Secondly, in order to verify the effectiveness of the improved RC4 algorithm which has improved the randomness of sequences, three standard tests has been used and the experiment result is obtained by simulation software. Thirdly, in case that the users may encrypt information by simple key which makes low complexity, we improve the matrix encryption algorithm with double encryption for graphics which keeps the feature of QR code and ensures the highly security of QR code information.