Security of Public Watermarking Schemes for Binary Sequences

Abstract

Abstract. In this paper, we focus on the security aspect of public watermarking schemes. Specifically, given a watermarked sequence I, we consider smart attackers whose task is to find a non-watermarked sequence I using as few calls to the publicly available detection routine as possible. We restrict the media to binary sequences and use Hamming distance as the measure. We study a class of watermarking schemes and give an attacker who uses expected O(d(1 + log(n/k))) calls to find such I , where d and k are determined by the false alarm and distortion of the scheme, and n is the length of the sequence. This attacker is optimal when k = o(n). By taking the number of calls required as a measure of the security, we can trade-off the requirements on security, false alarm and distortion.