Research On Methods Of Financial Documents Content Authentication Based On Watermarking

As an important application of information hiding technology, digital watermarking has provided a new solution to protect the copyright of multimedia information and to use its content legitimately. Above of all, using the fragile digital watermarking to guarantee the authenticity and integrity of multimedia contents has its unique superiority. Now along with electronic commerce and the E-government has been vigorously promoted, the corresponding financial profession's information construction is also progressing by leaps and bounds development. Because financial documents are very important, the very slight distortion possibly causes the huge economic losses, therefore it is very significant to carry on the content authentication.When storing and transmitting the financial documents we can use image content authentication technology to realize finance information content protection in order to prevent the illegal user from editing or changing the effectively if transform documents into the pictures format firstly. After widespread investigation then analysis massive Chinese and foreign literature and study current fragile watermarking technology's development, this article designs one security fragile watermarking system to be suitable for the financial documents content authentication .This watermarking system can distinct the contents of financial documents such as the bill and so on. When the documents have been maliciously distorted, the system can locate and characterize altered regions, furthermore recover the tampered data.This article's prime tasks and innovations are as follows:1)After transforming the financial documents information into the picture format firstly, take its whole primitive picture as carrier image to carry on division, then select a block region as distortion localization watermarking which size is the same as division block regions', select the important region block data as recovering watermarking too. Revising picture element value of distortion localization watermarking in order to change it into two value image, and then use the least significant bit algorithm to insert it into the primitive carrier important region blocks, when the documents have been maliciously distorted the algorithm can locate and characterize altered regions.2 ) Introduce the basic definition of wavelet and the characteristic of multi-resolution analysis, specially the stationary picture decomposition and restructuring principle based on two-dimensional separate cosine wavelet. After wavelet transformation and considering the wavelet coefficient's structure and characteristic of image, propose a method of inserting watermark into the wavelet transformation territory by using quantification modulation system.3 ) After encrypting recovering watermarking then carry on scrambling pretreatment. The encryption algorithm used in this article is a new algorithm based on the chaos sequence encryption, the result is varied because initial parameter's selection and encryption matrix's generation type is different, which has increased the password space; Moreover through scrambling pretreatment, on the one hand may further strengthen the watermarking system's security, on the other hand may strengthen ability which watermarking withstand the duplication attack and chaotic attacks.4)Design a safe financial documents content authentication protective system, and realize the algorithm which this article has proposed. Insert localization watermarking into the financial documents important region block and insert pretreated recovering watermarking in unimportant region block by using wavelet territory quantification modulation method. Through doing massive simulation experiments has proven this plan is superiority when examines and recovers the spot where the documents content is partially revised, which can effectively avoid the losses caused by the aggressor revising the documents content or forging watermark information arbitrarily.