Recoverable Fragile Watermarking Algorithm For Image Content Authentication

Currently, computer network technology develops much more and more quickly,the storage, dissemination and assignment of multimedia files, such as images, text,audio, video, become easier and easier, which will undoubtedly bring greatconvenience to people’s lives. However, malicious network attacks as well astampering of multimedia file content are becoming more and more rampant, digitalimage thus become the main object of lawless attacks of multimedia files. Therefore,how to effectively and reliably protect the authenticity and integrity of digital imagecontent becomes contemporary social problems to be solved.The common means of digital image content protection includes: cryptographymethod, digital digest method and digital watermarking method. Cryptographymethod achieves the purpose of information hiding by encoding the original data.However, when the encryption key is obtained by illegals, it becomes very difficult toprotect the integrity and authenticity of file content; digital digest method producesthe digital digest of the protected files, detect the changes of images by the changes ofdigital digest in the certification process. The method has high security, but has largeburden of channel transmission, and the summary information is required to betransmitted with the documents, causing additional consumption of the transmissionchannel; digital watermark technology embeds some information (watermark) in theimage without losing visual quality of digital images, realizing the purpose of imagecopyright protection, by detecting the authenticity and integrity of digital imagecontent.In this paper, in order to effectively enhance the ability of the tampered areapositioning for image content and recovery the image tampering area, the method ofrecoverable fragile watermarking technique for image content authentication isproposed. Knight Parade strategy is combined to scramble original watermark. Toensure the sensitivity of algorithm to the operations of digital contents, we usedifferent coefficients of the DCT high-frequency domain of the host image to hide thefragile watermark repeatedly; propose the concept of the relevant block, and hide gray information of pixel blocks for completing the restoration of its corresponding block.In addition, the simulation experiments of the proposed method are designed,and an image content authentication system is proposed. The experimental resultsshow: the system can accurately locate the tampering area, and can recover thecontent of the tampered area.Overall, the proposed fragile digital watermarking algorithm can effectivelyprotect the authenticity of the digital image content. Relative to the previousalgorithm, the security and the tampering positioning capability has been greatlyimproved. Image content authentication system meets the basic requirements better,providing greater convenience to users on digital image content certification.