26, No. 7, Oct. 5, 2006
Digital fingerprints could
combat multimedia piracy
Maureen Wilkey, ECE student intern
photo to enlarge
by Brad Petersen
paper co-written by Negar Kiyavash (right), a
doctoral student, and Pierre Mouline, a professor,
both in the department of electrical and computer
engineering, recently won the Best Student Paper
Award in the multimedia signal processing area
at the International Conference on Acoustics, Speech
and Signal Processing held in Toulouse, France.
The paper, titled “On Optimal Collusion Strategies
for Fingerprinting,” discusses methods for
using digital fingerprinting to trace pirated multimedia
While police use fingerprints to determine who stole a piece of property or handled
a murder weapon, engineers may soon be able to use digital fingerprints to determine
who pirated a multimedia file.
“The applications go
far beyond the movie piracy. Any multimedia content or form of intellectual
property that you can imagine can be subjected to collusion attacks,
and these attacks are facilitated by availability of peer-to-peer networks.”
Negar Kiyavash, a UI doctoral student in electrical and computer engineering,
is helping in the battle against multimedia piracy. Her recent paper, titled “On
Optimal Collusion Strategies for Fingerprinting,” won the Best Student
Paper Award in the multimedia signal processing area at the International Conference
on Acoustics, Speech, and Signal Processing (ICASSP) in Toulouse, France.
Kiyavash won a $500 prize for her paper and is planning to continue her research
on the subject for several more years.
Pierre Moulin, a professor of electrical and computer engineering and a researcher
at the Beckman Institute for Advanced Science and Technology, is co-author of
the paper. Moulin and Kiyavash have been researching theory and applications
for digital fingerprinting. For instance, one could make each copy of a DVD or
music file slightly different so that if it is tampered with, engineers can determine
who the culprit was. A strong challenge to digital fingerprinting is mounted
when two or more people collude to create a forgery that combines their individual
copies, so that this forgery cannot be easily traced to the colluders involved.
“The first step is to find what the worst attack is,” Kiyavash said. “The
best way for colluders to avoid being caught is to try to make the forgery as
close to the original as possible, to reduce the visibility of the fingerprints.”
Kiyavash said that the more people collude, the harder it is to determine who
colluded. According to Moulin, much research went toward identifying the maximum
number of colluders that the fingerprinting system can cope with, i.e. the system
can detect the fingerprint of at least one of the colluders.
“There are definite limits to what we could identify,” Moulin said. “For
instance, depending on the nature of the media signal, we could be successful
if there are as many as 100 colluders, but not 1,000.”
Kiyavash said that the more users there are, the less robust the fingerprinting
system is, and the harder it is to identify a colluder. There is a tradeoff between
the number of users and the number of colluders you can tolerate.
While Hollywood is already using the technology, especially in limited release
films, Kiyavash said the technique is relatively new, and she is looking forward
to improving it over the next few years.
“It’s very mathematical. Information theory, signal processing and
coding theory, all play a central role and they are all very close to my heart,” Kiyavash
said. She will finish her doctorate this fall and will continue her research
as a postdoctorate fellow at the university in the spring.