ppt on cryptography .pdf download

Abstract:

This paper proposes to introduce public-keycryptography into digital atermarking
so that all the informationfor extracting a watermark can be opened. In the proposed
system,a watermark is embedded into “an encrypted-image with a publickey”, then the
watermarked encrypted-image is decrypted usingthe corresponding private key. Using the
opened information suchas the public key and the extracting algorithm, any one can
extracta watermark from a watermarked image. Any cracker whodoesn’t possess the
private key can not defuse nor alter awatermark. It should be noted that in the system, the
watermarkedimage would differ considerably from the original image, sincesmall noise
embedded on the encrypted-image is usually expandedwhen it is decrypted. This paper
also shows the possibility to solvethe problem.

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