Research Of QR Code Encryption Method Based On Cellular Automata

With the widespread use of the smart mobile phone, QR code has stept inpeople’s life gradually. The QR code has been applicated in webpage skipping,recommending advertisements and other fields. At the same time, it also plays theadvantages of convenience in the mobile phone payment, ticketing system, securityand law enforcement fields. However, as the result of the problems of theinformation leakage caused by QR two-dimensional code, economic property lossevents occur frequently. In order to prevent the information of QR code from readand tampered by malicious individuals or institutions, it is necessary to encrypt theQR code before it has been stored and transmited. QR code belongs to the two valueimage of the digital image. Therefore, the encrption method in this paper is the onebased on the digital image.The two typical QR code encryption methods have been analysed by combiningtheoretical research with simulation experiment. We adopt a kind of encryptionmethod of QR code based on ECA state ring in allusion to the simple keys of existingencryption method, the long time spent in encryption and decryption process and theloss of the original functional characteristics of QR code after encryption and so on.Due to elementary cellular automata has the advantages of simple structure highlyparallel, using the ring of elementary cellular automata to deal with the pixels in theQR code except for those show functional information. It is showed in the simulationexperiment that the method has some improvement in speed compared with the twotypical methods of the QR encryption. And the encryption image saves the functionalinformation of the original QR code. But there is no enhancement in security. Then aQR code encryption method based on RCA state ring has been adopted in order toimprove the the security of the QR code encryption method based on ECA state ring.In addition to the pixels which show fuctional information are scrambled randomnumber times by using the constructed regulation of RCA. The simulation results show the encryption method based on RCA has better diffusivity, stronger ability toresist brute force attack and better resistance to key attack. The method’s security hasbeen proved by testing the key space, key sensitivity, adjacent pixels correlationcoefficient and gray scrambling degree index. And the method can make a balance ofthe security and the speed of encryption by adjusting the parameter seed.