谁有它的密码？

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ISC2 CISSP Study Guide 2003 - Password CISSPSG2003.pdf

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There are several attacks in current digital watermark system. In first case,\r\nwe can suppose that Alice and Bob use the same digital watermarking technique\r\nto watermark and there is one unique decoding scheme to extract the labels\r\nembedded in the images. In this case, if a watermarked image contains both\r\nAlice and Bob’s signatures, how can we decide the originality of this marked\r\nimage? And we also think another scenario. Let’s suppose that Alice and Bob\r\nuse different watermarking techniques. And Given a watermarked image, Alice\r\ncan take this image and decode the label using her decoding scheme. Similarly\r\nBob can perform the label extraction process with his decoding scheme. If Alice’s\r\ndecoder indicates that the image belongs to her while Bob’s decoder indicates\r\nthat it is his image, then how can we decide the ownership of this marked image?\r\nIn these two cases, rightful ownership cannot be resolved by invisible watermarks\r\nalone. They present in detail a counterfeit watermarking scheme that allows\r\nmultiple claims of ownerships.\r\nUndeniable watermark differ from ordinary digital watermark in that the\r\nverifier should be unable to distinguish between valid and invalid watermark.\r\nBut, original watermarker can change it into correct one. If the message in is\r\ncopyright owner’s information, the scheme can be non-invertible. And we can also\r\nintroduce zero-knowledge based watermarking mechanism. Using zero-knowledge\r\nprotocols[3], watermarks can be made public enough to be detected yet private\r\nenough to be unremovable. i.e., watermarking scheme in which the watermark’s\r\npresence can be verified without ever revealing enough information to remove\r\nthe mark.\r\nDesignated Verification of Digital Watermark 1071\r\nWe first present the overall digital watermark mechanism and review the\r\nexisting model in section 2. We then consider re-watermarking attack and its\r\npossible solution in section 3. And then we propose designated verification process\r\nwith commitment scheme in section 4. Furthermore, we discuss the proof\r\nof ownership in section 5 and conclude this study with the consideration of the\r\nfuture works in final section.