• Journal of Korea Multimedia Society
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• v.10 no.5
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• pp.569-582
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• 2007

Digital watermarking technique for copyright protection and prevention of illegal copy and distribution can provide the reliable transaction to both buyer and seller in e-commerce through the cryptographic protocol such as 'Buyer-seller watermarking protocol'. Recently there has been researched about some cryptographic protocols for watermarking system but there has no yet mentioned about the implementation of practical watermarking technique in protocol. This paper presents the watermark embedding technique based on POCS in buyer-seller watermarking protocol. The proposed method designs the robust convex set based on EZW and the invisible convex set using PSNR and then projects into two sets until the convergence condition is satisfied. Experimental results verified that BER of watermark that is embedded by the proposed method has lower 0.02-0.10 than BER of the conventional method.

• Review of KIISC
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• v.11 no.3
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• pp.90-99
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• 2001

디지털 컨텐츠의 지적 재산권 보호를 위한 디지털 워터마킹 기술이 많이 연구되어져 왔다. 핑거프린팅은 디지털 컨텐츠 지적 재산권 보호를 위한 또 다른 기술로서, 디지털 워터마킹에서는 컨텐츠 내부에 소유권자나 판매권자의 정보 가 삽입되는 반면에, 핑거프린팅에서는 구매자의 정보가 삽입이 된다. 따라서, 핑거프린팅을 이용하면 불법적으로 컨텐츠를 재분배한 구매자가 누구인지 밝혀낼 수 있기 때문에, 구매자들로 하여금 불법적인 재분배하려는 의욕을 저하 시킬 수 있다. 이러한 핑거프린팅 프로토콜 중에서 익명 핑거프린팅 프로토콜은 합법적인 구매자에 대해서는 익명성 을 보장해 주며, 불법적인 재분배자에 대해서만 신원을 밝혀낼 수 있도록 하는 프로토콜이다. 이 논문에서는 현재까지 연구된 익명 핑거프린팅 프로토콜에 대해서 비교 분석하고, 익명 평거프린팅 프로토콜에서 충족되어야 하는 요구사항 들을 살펴본다.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.5
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• pp.396-403
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• 2009

An anonymous asymmetric fingerprinting protocol combined with watermarking techniques, is one of the copyright protection technologies keeping both right of a seller and that of a buyer, where a seller and an anonymous buyer perform such a protocol that employs various cryptographic tools in order that the seller does not know the exact watermarked copy that the buyer receives, while inserting an invisible non-removable fingerprint i.e., each different unique watermark, into each copy of the digital content to be sold. In such a protocol innocent buyers are kept anonymous during transactions, however, the unlawful reseller is unambiguously identified with a real identity as a copyright violator. In 2007, Yong and Lee proposed an anonymous asymmetric fingerprinting scheme with trusted third party. In this paper we point out the weakness of their scheme such as: the buyer with intention can remove the fingerprint in the watermarked content, because he/she can decrypt the encrypted fingerprint with a symmetric key using man-in-the-middle-attack; a real identity of a buyer can be revealed to the seller through the identification process even though he/she is honest. Furthermore, we propose an improved secure and efficient anonymous asymmetric fingerprinting scheme which enables to reduce the number of communication between the participants.

• Journal of Korea Multimedia Society
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• v.17 no.7
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• pp.778-786
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• 2014

Buyer-seller watermarking protocol is one of the copyright protection techniques which combine a cryptographic protocol used in electronic commerce with a digital wetermarking scheme aiming at proving the ownership of multimedia contents and preventing the illegal reproduction and redistribution of digital contents. In this paper, it is proposed a new watermarking scheme in an encrypted domain in an image that is based on the block-DCT framework. In order to implement watermarking scheme in a public-key cryptosystem, it is divided that frequency coefficients exist as real number into integer and decimal layer. And the decimal layer is modified integer type through integral-processing. Also, for robustness and invisibility required in watermarking scheme, it is designed a direction-adaptive watermarking scheme based on locally edge-properties of each block in an image through analyzing distribution property of the frequency coefficients in a block using JND threshold.