Fast and adaptive tracing strategies for 3-secure fingerprint watermarking codes

Fingerprinting codes are mechanisms to increase the security of transaction watermarking. Digital transaction watermarking is an accepted mechanism to discourage illegal distribution of multimedia. Here copies of the same content are distributed with individual markings. Simple but effective attacks on transaction watermarking are collusion attacks where multiple individualized copies of the work are compared in order to detect and attack the watermark positions and thus create a counterfeited watermark. One common countermeasure is given by fingerprinting codes. The main challenge is to provide codes which are highly secure, reliable and, at the same time, provide a sufficiently compact code length according to the payload limitations of current watermarking algorithms. Applying such codes in practice, the codes have to face additional challenges: Most operators arrogate small amounts of time for the code generation and embedding process and for the detection and accusation process. In this article, we describe a new fast but fair fingerprinting code to detect a collusion of up to three colluders. The code is very flexible and consciously kept simple to be adaptive and fast in order to stay applicable for all demands of potential appliers. Using accusation sums we are able to make a decision about which kind of attack strategy the colluders may have used. Accordingly the algorithm is split into two different tracing strategies. Both are based on discarding as many fingerprints as possible and only consider the most suspicious.