Paper forgery is among the leading causes of corruption in many developing regions. PaperSpeckle is a low-cost, robust, tamper-resistant paper watermarking technique that extracts a unique watermark for any piece of paper based on the natural randomness present in the structure of the paper .
Our goal in developing PaperSpeckle is to build a low-cost paper based authentication mechanism for applications in rural regions such as microfinance, healthcare, land ownership records, supply chain services and education which heavily rely on paper based records.
Unlike prior paper watermarking techniques that have extracted watermarks based on the fiber structure of paper, PaperSpeckle uses the random speckle pattern, a random bright/dark region formation at the microscopic level when light falls on to the paper, to extract a unique watermark to identify paper. In PaperSpeckle, we show how to extract a "repeatable" speckle pattern of paper of a small region using low-cost machinery involving paper, pen and a cheap microscope; existing speckle works have used complicated high precision lasers to extract these speckle patterns of objects. Since speckle patterns exhibit variations due to orientation changes, PaperSpeckle uses a combination of several well-established image processing algorithms to compare two speckle patterns. We have tested PaperSpeckle on different types of paper and also have shown that it can produce a robust repeatable watermark even if paper is damaged due to folding, crumpling, soaking in water/oil or aging with time.