Group-Oriented Anti-Collusion Fingerprint Based on BIBD Code

Digital fingerprinting is a technique for identifying unauthorized copy and tracing back to its user. The distributor marks each individual copy with a unique fingerprint. At present, the fingerprinting scheme generally has many difficulties and disadvantages for large-size users. To solve these problems, this paper presents a new fingerprint code which is composed of an outer RS (Reed-Solomon) code and an inner code based on BIBD (balanced incomplete block design) code. In practical applications, the probabilities of taking part in collusion in different combinations are varied. So we use group-oriented fingerprint to shorten fingerprint length. Performance of the algorithm is proved and analyzed by theory. Compared with traditional codes for digital fingerprint, under the same collusion size and error probability, the algorithm shortens digital fingerprint length greatly.