Research On Color QR Code Watermarking Based On Chaotic Encryption

The QR code is a two-dimensional matrix symbol invented and started to be used by Denso Wave in 1994.It has the advantages of large amount of information,high stability,low cost and easy popularization.It also supports Chinese characters,URL addresses and images and many other kind of information,is widely used in modern society.Due to the low QR code threshold,malicious users can attach malicious information in the QR code and spread it through the Internet.Therefore,the security verification and copyright protection of QR codes are very important.In order to improve the security of color QR codes,this thesis proposes a color QR code digital watermarking algorithm based on chaos encryption.The main work of this thesis is as follows:1)The chaotic encryption theory is studied,including Logistic mapping algorithm and Chebyshev mapping algorithm.It is found that the traditional digital image chaos encryption algorithm has the problems of limited accuracy and stochastic degeneracy.To solve this problem,this thesis proposes a digital image chaos encryption algorithm based on variable parameters.This algorithm changes the parameters of one-dimensional Logistic chaotic system into variable parameters,expands the range of chaos system,greatly increases the difficulty of malicious user calculate the encryption key through the return mapping analysis and other means and enhance the robustness of the encryption algorithm.2)In this paper,the digital image chaotic encryption algorithm based on variant parameters is applied to the field of color QR code copyright protection and security verification.A color QR code digital watermarking algorithm based on chaotic encryption is proposed.The algorithm firstly uses the improved image chaos encryption algorithm to encrypt the watermark,and then divides the image into several sub-blocks.According to the human visual system,the sub-block to be embedded in the watermark is selected,and the watermark is embedded using discrete wavelet transform.This thesis uses MATLAB to simulate the watermark embedding,extraction process.Experiments show that compared with the reference algorithm,the proposed color QR code digital watermarking algorithm based on chaos encryption possess es good invisibility,and the extracted watermark image has high definition,and the algorithm can well resist the common noise attacks and geometry attacks,it has high value in the field of color QR code copyright protection and security verification.