A low-rate fingerprinting code and its application to blind image fingerprinting

In fingerprinting, a signature, unique to each user, is embedded in each distributed copy of a multimedia content, in order to identify potential illegal redistributors. This paper investigates digital fingerprinting problems involving millions of users and a handful of colluders. In such problems the rate of the fingerprinting code is often well below fingerprinting capacity, and the use of codes with large minimum distance emerges as a natural design. However, optimal decoding is a formidable computational problem. We investigate a design based on a Reed-Solomon outer code modulated onto an orthonormal constellation, and the Guruswami-Sudan decoding algorithm. We analyze the potential and limitations of this scheme and assess its performance by means of Monte-Carlo simulations. In the second part of this paper, we apply this scheme to a blind image fingerprinting problem, using a linear cancellation technique for embedding in the wavelet domain. Dramatic improvements are obtained over previous blind image fingerprinting algorithms.