Abstract: A wavelet-based adaptive public key watermarking algorithm is presented in the paper. Data owner can use his private key embed the identification into the local image and retrieve it from the watermarked image. The data users can use the public key detect the identification from the watermarked image. How much the embedding strength is adjusted adaptively to the local image characteristics. The experimental results have shown that the proposed watermark is invisible to human eyes and very robust to joint photographic experts group compression attack, crop attack and so on.