• Journal of KIISE:Computer Systems and Theory
• /
• v.34 no.7
• /
• pp.288-295
• /
• 2007

The illegal copying and redistribution of digitally-stored information is a crucial problem to distributors who electronically sell digital data. fingerprinting scheme is a technique which supports copyright protection to track redistributors of electronic information using cryptographic techniques. Anonymous asymmetric fingerprinting scheme prevents the merchant from framing a buyer by making the fingerprinted version known to the buyer only. And this scheme allows the buyer to purchase goods without revealing her identity to the seller. In this paper, a new anonymous asymmetric fingerprinting scheme with TTP is introduced. The buyer's fingerprint is generated by the Fingerprint Certificate Authority which is a TTP. When the seller embeds the fingerprint in the digital data, the protocol uses the homomorphic encryption scheme. Thus the seller cannot know the buyer's fingerprint and the buyer's anonymity is guaranteed by using anonymous key pair.

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

• Proceedings of the Korea Multimedia Society Conference
• /
• 2002.11b
• /
• pp.229-233
• /
• 2002

디지털 핑거프린팅(digital fingerprinting)은 멀티미디어 컨텐츠에 구매자의 정보를 삽입하여 불법적으로 컨텐츠를 재분배한 부정자(traitor)를 추적하는 기법이다. 기존에 제안된 대부분의 핑거프린팅 기법은 부정자를 식별하는 단계(identification protocol) 또는 그 증거를 제 3자에게 제출하여 확신받는 단계(trial protocol)까지만 고려했다. 대개의 경우 판매자는 해당 컨텐츠에서 부정자의 정보를 추출하여 그 신원을 확인하므로 재분배자 식별 단계를 거친 판매자는 해당구매자의 정보를 알 수 있게 된다. 따라서 판매자는 이를 이용하여 원 컨텐츠에 해당 구매자의 정보를 삽입할 수 있으며, 이로 인해 또 다른 문제가 발생할 수 있다. 본 논문에서는 재분배자 식별 단계 이후, 판매자가 불법적으로 구매자의 정보를 컨텐츠에 삽입할 가능성을 제기하고, 이 문제를 해결하기 위해 2단계 핑거프린팅 기법을 이용한 익명 핑거프린팅 방식을 제안한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2005.07a
• /
• pp.235-237
• /
• 2005

디지털 형식으로 저장되어 있는 데이터의 불법적인 복사와 재분배는 전자상거래 상에서 디지털 컨텐츠를 판매하는 상점에게 매우 큰 문제가 된다. 핑거프린팅 기법은 암호학적인 기법들을 이용하여 디지털 컨텐츠를 불법적으로 재배포한 사용자를 찾아냄으로써 저작자의 저작권을 보호한다. 비대칭적 핑거프린팅 기법은 대칭적인 기법과 달리 사용자만이 핑거프린트가 삽입된 컨텐츠를 알 수 있어 사용자가 컨텐츠를 재배포했을 경우만 사용자가 고발되는 기법이다. 본 논문에서는 신뢰기관을 이용한 비대칭적 핑거프린팅 기법을 제안한다. 사용자의 핑거프린트는 신뢰기관이 생성하고 사용자의 익명공개키 쌍과 준동형의 암호를 이용하여 컨텐츠에 핑거프린트를 삽입함으로써 상점은 사용자의 핑거프린트를 알 수 없도록 하여 비대칭성을 만족하여 컨텐츠가 재배포되었을 경우 상점은 신뢰기관으로부터 정보를 받아 재배포자를 추적할 수 있다.

• Journal of KIISE:Computer Systems and Theory
• /
• v.31 no.5_6
• /
• pp.353-359
• /
• 2004

The illegal copying and redistribution of digitally-stored information is a crucial problem to distributors who electronically sell digital data. Fingerprinting scheme is a techniques which supports copyright protection to track redistributors of electronic information using cryptographic techniques. Anonymous fingerprinting schemes, differ from symmetric fingerprinting, prevent the merchant from framing a buyer by making the fingerprinted version known to the buyer only. And the scheme, differ from asymmetric fingerprinting, allows the buyer to purchase goods without revealing her identity to the merchant. In this paper, a new anonymous fingerprinting scheme based on secret sharing is introduced. The merchant finds a sold version that has been distributed, and then he is able to retrieve a buyer's identity and take her to court. And Schnorr's digital signature prevents the buyer from denying the fact he redistributed. The buyer's anonymity relies on the security of discrete logarithm and secure two-party computations.

• KIPS Transactions on Computer and Communication Systems
• /
• v.11 no.4
• /
• pp.127-132
• /
• 2022

An anonymous encrypted communication networks that make it difficult to identify the trace of a user's access by passing through several virtual computers and/or networks, such as Tor, provides user and data privacy in the process of Internet communications. However, when it comes to abuse for inappropriate purposes, such as sharing of illegal contents, arms trade, etc. through such anonymous encrypted communication networks, it is difficult to detect and take appropriate countermeasures. In this paper, by extending the website fingerprinting technique that can identify access to a specific site even in anonymous encrypted communication, a method for specifying and classifying service types of websites for not only well-known sites but also unknown sites is proposed. This approach can be used to identify hidden sites that can be used for malicious purposes.