| QR code,as a bridge between online and offline,has a wide range of applications in daily life.Among them,mobile payment is the most typical application scenario.The rapid development of Internet and e-commerce has greatly changed the traditional business model and consumption habits.With the promotion of major IT and e-commerce companies at home and abroad,mobile payment technology has emerged and achieved considerable development.Mobile payment technology based on QR code is popular among users because of its fast,efficient and low cost,and its position in the booming mobile payment industry is gradually enhanced.But the following payment security issues are also worrying: Counterfeit QR code dissemination,payment code stolen,business and user information maliciously read or tampered with,identity information leakage and other issues occur from time to time,endangering user privacy and property security incidents are increasing year by year,while we enjoy the convenience of QR code mobile payment technology to people's shopping and consumption.QR code,as a kind of image information carrier,is highly compatible with image encryption technology.Therefore,this paper takes QR code payment scenario as the research object,combines cellular automaton image encryption algorithm and Joseph ring scrambling algorithm,and designs a compound encryption method with high security.1.In image encryption,QR code,as the carrier of user and payment information,is vulnerable to malicious reading and other attacks.Therefore,some security risks can be avoided by adopting encryption measures.The image encryption algorithm based on cellular automaton is very suitable for QR code encryption scenarios.Therefore,the QR code is encrypted by an image encryption algorithm based on two-dimensional bi-state Five-neighborhood reversible cellular automaton.The core of the algorithm is composed of main and sub-CAs,in which the main CA is used for two-dimensional code information encryption iteration operation and needs to satisfy reversibility;the sub-CA generates boundary conditions based on key seed image and participates in tail data protection operation.The main CA is constructed as follows: the neighbor structure adopts partial X2 structure with obvious confusion effect,and the CA iteration rule is 96699669(hex)reversible rule;the sub-CA is constructed as follows: the neighbor structure adopts von Neumann type,and the CA iteration rule is 9d62(hex)chaotic behavior rule.2.In terms of scrambling algorithm,starting with the classical Joseph ring problem,this paper further studies the periodic characteristics of Joseph ring mathematically.Joseph ring scrambling algorithm contains three parameters: STEP,M0 and N,which represent the step length,initial position and sequence length of Joseph scrambling respectively.The selection of different parameter values will change the periodic characteristics of Joseph rings,which can generate chaotic sequences with various rules.In this paper,the method of determining Joseph ring period and Joseph regular space under arbitrary parameters is studied,and it is analyzed by combining the knowledge of N-order permutation group in abstract algebra.According to the above theory,this paper designs a composite image encryption method: this method uses Joseph scrambling algorithm as the pretreatment part of image encryption,cellular automaton as the core part of image encryption,and scrambling storage of user's private key in key management.Then,QR code payment simulation experiment is carried out to test the uniform average change intensity and the correlation of adjacent pixels.The cryptographic effect of the algorithm is evaluated by such criteria as the standard index and so on.The experimental results show that the algorithm can effectively protect the transaction information and user identity information carried by QR code,and improve the security of mobile payment of QR code. |
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