Design of Collusion-Free Codes Based on MAI-Free Principle

The design of collusion-free codes for data hiding systems is investigated, and two new collusion-free codes are proposed in this work. They are called the Orthogonal Spreading (OS) codes and the Orthogonal Spreading codes with Inverse discrete Fourier Transform (OSIFT). The design of OSIFT codes is motivated by the recently developed multi-access-interference-free (MAI-free) codes in an orthogonal frequency division multiplexing (OFDM) wireless communication system. Code embedding and detection algorithms are described. It is shown by simulation that both OS and OSIFT codes are robust against collusion attacks in an exemplary audio watermarking system.