Collaborative Research: Digital Fingerprinting: Information Theoretic Analysis and Code Design
The problem of fingerprinting for copyright protection has come to the forefront of research in information and coding theory, motivated by varied applications such as digital fingerprinting of software, images, audio signals as well as multimedia fingerprinting for video-on-demand and related applications. Copies of data distributed to the users of the system are protected by digital fingerprints,i.e., short strings of bits designed individually for each user of the system in such a way that individual users cannot redistribute their contents without being traced by the distributor of the system. The tracing becomes substantially more difficult when coalitions of users cooperate to create a pirate copy of the data, attempting to obfuscate their fingerprints. The prime objective of this research is to use information-theoretic and coding methods to establish the maximum number of users of a system with reliably fingerprinted data and to construct new, large-size fingerprinting schemes. This research considers two main models of the fingerprinting system, one in which the pirates first detect the positions of the fingerprint by comparing their copies of the data, and then form a fingerprint for the unregistered copy, and the other in which they are allowed to alter their data files as long as the unregistered copy created satisfies some distortion constraints as compared to their original copies. Representing fingeprinting systems as multiple-access channels, either fixed or time-varying, this research establishes the capacity limits of fingerprinting under these two models. New fingerprinting codes are constructed equipped with efficient identification/tracing algorithms and related performance bounds. Finally, this research investigates the properties and designs new families of combinatorial coding schemes such as separating and frameproof codes, codes with the identifying parent property, and traceability codes.
