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Digital Sealing Based on Double Watermarks

By integrating adaptive robust watermark and simplified fragile watermark, a digital sealing scheme is proposed. The digital seal, which resembles conventional one, shows robustness against attacks like Gaussian noise, median filtering, JPEG compression and cropping. Furthermore, any modification of the seal can be detected. Consequently, the digital sealing technique fulfills the purposes of confidentiality, authentication, integrity and non-repudiation.