A simple way to determine the uniqueness of a sheet of paper

American security experts have found a simple way to reliably determine the uniqueness of paper documents with a cheap household scanner. They proved that even at a resolution of 600 dpi, you can identify the structure of a blank sheet of paper and build on its basis a 3D model that will be unique to this particular sheet.

The technology can be widely used to verify the authenticity of paper documents, including passports, bank notes, tickets, etc. In addition, the technology can be used to determine the true origin of "anonymous" paper artifacts, such as ballots in the ballot box.

This is what a sheet of paper looks like under a microscope.
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Clearly visible individual wood fibers that form a unique pattern.

If you scan the sheet on an ordinary household scanner, the picture will appear white, but if you select a small piece of the image and adjust the contrast, the result will be something like this.



Dark areas form where the shadow of the scanner lamp forms due to the paper structure. If you rotate the sheet and scan again, the shadows will fall at a different angle. This allows us to create a three-dimensional model of the surface of the paper. For example, if there is text printed on a laser printer on a sheet, then the areas with toner particles will clearly rise above the surface.



The results of their work, scientists have published in the “Fingerprinting Blank Paper Using Commodity Scanners” , which will be published in the May issue of the journal “Proceedings of the IEEE Symposium on Security and Privacy” .

via Freedom to Tinker (blog of one of the authors of the study)