Authentication and Tamper Localization of scanned Bill and Seal based on Block Correlation

For important financial documents such as financial statements, financial contracts, bills, accounts, etc., even if there is a very small change in the transmission process, it may lead to huge economic losses, so it is of great significance to verify the content. In addition, the seal symbolizes an undeniable identity, so it should be absolutely credible. In this paper, we propose a method of passive authentication based on the block correlation to distinguish whether or not the documents have been tampered with semantics in the process of circulation after the paper documents are imaged, and then locate the tampered area. Through a large number of experiments, the results show that the tamper detection accuracy and location accuracy of the bill image are up to 96% and 92% respectively; the tamper detection accuracy and location accuracy of the seal are up to 93%) and 88% respectively.