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In this paper, we propose a buyer authentication scheme that ensures copyright protection of multimedia objects. We show that the authentication mark is robust and recoverable in spite of a number of intentional attacks to destroy the authentication mark. The authentication mark is introduced in the wavelet space. The wavelet coefficients of the multimedia signal are randomly grouped into a number of disjoint subsets of the wavelet coefficients. However, the manipulation of the wavelet coefficient is such that the signal quality is always within the just noticeable distortion (jnd) limit. The buyer specific key survives even though we assume that a potential forger knows the proposed authentication scheme and this knowledge can be used as an attack.