New Technique – Fingerprint Paper
A security research team led by popular computer science professor Ed Felten has just finished a study into whether 
future anticounterfeiting measures might have more luck if they focused on the print medium itself. Is it possible to fingerprint a single sheet of paper? The answer is yes, it can be done with commodity hardware.
They 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, they generate a concise fingerprint that uniquely identifies the document.
The fact that Felten’s method takes advantage of a commodity scanner is important. Felten’s primary contention is that this commodity-driven scanning method is both low-cost and robust.
A modern scanner isn’t capable of scanning at that level of detail, but Felton points out that if you scan a document, blow up one corner, digitally enhance it, and then do this from different angles, one can “map out the tiny hills and valleys on the surface of the paper.” Print a word on the scanned section.
The Felten’s fingerprint system is designed to satisfy security and usability goals:
Uniqueness:
Every document should be identifiable and distinguishable from all others.
Consistency:
A fingerprint should be verifiable by multiple parties over the lifetime of the document.
Conciseness:
Document fingerprints should be short and easily computable.
Robustness:
It should be possible to verify a finger-printed document even if it has been subjected to harsh treatment.
Resistance to Forgery:
It should be very difficult or costly for an adversary to forge a document by coercing a second document to express the same fingerprint as an original.
The system stands up robustly in each of these cases, a fact that leads Felten and his team to consider the large number of potential applications for this security technology in the real world.
