Fingerprinting Paper
Fingerprinting Blank Paper Using Commodity Scanners
Will Clarkson, Tim Weyrich, Adam Finkelstein, Nadia Heninger, Alex Halderman, and Edward W. Felten
Abstract: This paper presents a novel technique for authenticating physical documents based on random, naturally occurring imperfections in paper texture. We introduce a new method for measuring the three-dimensional surface of a page using only a commodity scanner and without modifying the document in any way. From this physical feature, we generate a concise fingerprint that uniquely identifies the document. Our technique is secure against counterfeiting and robust to harsh handling; it can be used even before any content is printed on a page. It has a wide range of applications, including detecting forged currency and tickets, authenticating passports, and halting counterfeit goods. Document identification could also be applied maliciously to de-anonymize printed surveys and to compromise the secrecy of paper ballots.
RonK • March 19, 2009 7:40 AM
Seems like it might be also be an interesting side-channel to use for sending obscured key information. Still would require the physical transfer of a object between the two people.
An interesting offshoot might be an algorithm which derives a robust fingerprint from a digital image which is independent of the exact viewpoint of the camera — then two people could “agree” on a shared secret key by merely agreeing on a specific time and scene. Of course, this would be easily detectable if both photographers can be observed and their actions correlated in time. In fact, it starts to sound more like a movie plot than something really useful…. oh, well.