Research On Digital Watermarking Algorithm For QR Codes And Watermarking Image Authentication Code Verification Code

With the continuous development and innovation of science and technology,the Internet makes people access to means of resources and information becoming more convenient and efficient.But it also provides convenience for digital media infringement and illegal occupation of resources,having a serious impact on the security and stability of the Internet industry.Digital watermarking,as an effective means of copyright protection and information authentication,has been widely researched and used in many fields.Recently,with the emergence of new technologies,it affects the security of digital watermarking,in order to ensure watermark information's integrity,validity and security,digital watermarking not only need to have high strength's invisibility and robustness,but also need to gradually transform into diversification.In order to improve the ability of digital watermarking to resist external attacks,in the thesis,a new robust watermarking scheme was proposed,and it combined Quick response code(QR),chaotic system and DWT-DCT.Firstly,the chaotic system generating chaotic sequences used to encrypt QR.Secondly,processing the host image by DWT,then the low frequency sub-band was divided into blocks which its size 4*4,and performing DCT on the blocks.Finally,the watermark information is used to produce a 2 * 2 matrix,and adding it to the upper right corner of the DCT transform matrix.When the watermark information extracted,comparing the elements in the superposition matrix and the change rate of the elements to confirm the watermark information.The simulation results show that the scheme not only can enhance the transparency of the watermark information,but also can have strong robustness in cutting,graffiti,noise,filter and Jpeg compression attacks.With the rapid development of online image recognition technology and image processing technology,extracting the accuracy of image information is higher and higher,which poses a serious threat to the security performance of image verificationcode.Therefore,in the thesis,according to the current situation,and combined withthe characteristics of digital watermarking,a scheme based on digital watermarking image verification code is proposed.Firstly,chaotic encryption algorithm is used to ensure the security and uniqueness of the watermark information;Secondly,according to requirements to Embed watermark information;When user accesses the web page,selecting the picture by generating a random number;Finally,when the user's mouse through the picture,presenting the corresponding prompt words,the user through the matching prompt words and image information to determine whether the picture should be selected.The simulation results show that the average time of extracting watermark information and the server response time are shorter,and the watermark information has strong sensitivity.Thus by changing the embedded watermark information regularly can not only distinguish the similar image,but also in the practical use of the Internet to enhance the security of interactive platform.