Secure code design against collusion attacks for protecting digital content rights

This paper proposes a group-based collusion-secure code design technique for protecting copyrights on digital contents. Designing collusion-secure codes were difficult and there were problems in creating these codes in large numbers, as these codes should enable detecting collusion attacks when occurring in content with inserted forensic marks. In addition, there was a problem in applying these codes to actual services in that unique user-specific codes could not be issued. This paper proposes group anti-collusion codes (ACCs) made by introducing the concept of groups to existing balanced incomplete block design (BIBD) matrices. This would solve the problem of complexity in code design and increase the number of collusion-secure codes. For the group ACCs, problems in securing the uniqueness and verification of codes were overcome using set operations. Using the group ACCs, code complexity can be reduced when compared to existing collusion-secure codes, and code quantities can be increased when compared to code lengths.