Today, Tim Weyrich, Adam Finkelstein, Nadia Heninger, J. Alex Halderman, Ed Felten and I released our study on Fingerprinting Blank Paper Using Commodity Scanners. This result shows that individual sheets of paper are identifiable by their unique surface texture. The uniqueness of a document’s surface texture is the result of a random deposit of paper fibers during the manufacturing process. By exploiting a property of desktop scanners we are able to accurately and consistently measure the surface texture of a document, extract a fingerprint.

Once extracted, this fingerprint can be digitally signed and printed on the document, or stored in a database. The secrecy of a document’s fingerprint is achieved through the use of a secure sketch. You can think of a secure sketch as a fuzzy hash function. Similar inputs produce identical outputs, but knowing the output tells you provably little about the input. This is ideal for a situation where a document will be subjected to wear and tear. Wear and tear, as well as mis-alignment during scanning, can cause slight variations in a document’s fingerprint, which need to be corrected in order to successfully verify a document.


For more information, please see our website citp.princeton.edu/paper Read More...

If you are taking my COS 126 course, you can find the slides and materials here.

The Center for Information Technology (CITP) has moved into a new building. Sherrerd Hall is the wonderful new glass building across the way from the Computer Science building. We’ve got most of the 3rd floor as we tackle upcoming policy issues.




You can reach us at:

CITP
Sherrerd Hall, 3rd Floor
Princeton University
Princeton, NJ 08540

Or contact us via our website

Alex Halderman, Seth Schoen, Nadia Heninger, William Paul, Joe Calandrino, Ari Feldman, Jacob Appelbaum, Ed Felten and I released a paper on Thursday about our research on encryption keys that remain in memory even after the computer has been shutdown. The period of data remanence varies dramatically with temperature. We also describe ways to cool down the memory modules using common "canned air" products.

You can read the paper, get access to source code, and some videos explaining our result in more detail here.