Risk minimization in traitors within traitors in multimedia forensics

In digital fingerprinting and multimedia forensic systems, it is possible that multiple adversaries mount attacks collectively and effectively to undermine the forensic system´s traitor tracing capability. During this collusion attack, an important issue that the adversaries need to address is the fairness of attack and ensuring that all colluders share the same risk of being caught. This paper studies the dynamics among attackers in enforcing the fairness of collusion and investigates the problem of traitors within traitors, in which some selfish colluders wish to minimize their own risk while still profiting from collusion. We explore the strategies that these selfish colluders can use to further lower their probability of being detected and analyze their performance. We show that by processing their fingerprinted copies before multi-user collusion, the selfish colluders can further reduce their risk at the cost of quality degradation of their fingerprinted copies.