MIT/HP Alliance Colloquium: "Multimedia
Content Screening Using a Dual Watermarking and Fingerprinting System"
Dr. Henrique Malvar, Microsoft Research, 2:30-3:30pm, 37-252.
We present a new dual watermarking and fingerprinting system, where
initially all copies of a protected object are identically watermarked
using a secret key, but individual detection keys are distinct.
By knowing a detection key, an adversary cannot recreate the original
content from the watermarked content. However, knowledge of any
one detection key is sufficient for modifying the object so that
a detector using that key would fail to detect the marks. Detectors
using other detection keys would not be fooled, and such a modified
object necessarily contains enough information about the broken
detector key -- the fingerprint. Our dual system limits the scope
of possible attacks, when compared to classic fingerprinting systems.
Under optimal attacks, the size of the collusion necessary to remove
the marks without leaving a detectable fingerprint is superlinear
in object size, whereas classic fingerprinting has a lower bound
on collusion resistance that is approximately fourth root in object
size. By using our scheme one can achieve collusion resistance of
up to 900,000 users for a two hour high-definition video.
Joint work with Darko Kirovski and Yacov Yacobi.