Design of new fingerprinting codes using optical orthogonal codes

Digital fingerprinting has been proposed to restrict illegal distribution of digital media, where every piece of media has a unique fingerprint as an identifying feature that can be traceable. However, fingerprint systems are vulnerable when multiple users collude to create a forged copy by combining their ones. The collusion is modeled as a linear averaging attack, where multiple weighted copies are averaged and the Gaussian noise is then added to the averaged copy. In this paper, a new fingerprint design robust to collusion is proposed, which is to accommodate a lot more users than other existing fingerprint designs. A base matrix is constructed by cyclic shifts of binary sequences in an optical orthogonal code and then extended by a Hadamard matrix. Finally, each column of the resulting matrix will be used as a fingerprint. The focused detection is used to determine whether a user is innocent or guilty in a collusion of linear averaging attack. Simulation results show that the performance of our new fingerprint design is comparable to that of orthogonal and simplex fingerprints.