• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.805-816
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• 2017

Tor is a popular, low-latency open network that offers online anonymity to users by concealing their information from anyone conducting traffic analysis. At the same time, a number of conventional passive and active attacking schemes have been proposed to compromise the anonymity provided by the Tor network. In addition to attacks on the network through traffic analysis, interacting with an unsecured application can reveal a Tor user's IP address. Specific traffic from such applications bypasses Tor proxy settings in the user's machine and forms connections outside the Tor network. This paper presents such applications and shows how they can be used to deanonymize Tor users. Extensive test studies performed in the paper show that applications such as Flash and BitTorrent can reveal the IP addresses of Tor users.

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1314-1321
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• 2006

GSM(Global System for Mobile Communications) is a Pan-European digital cellular mobile system supporting widespread roaming and personal communication services in a worldwide wireless communication network. In suite of providing security capability, however, there are some problems like user authentication in GSM. In this paper, we propose the enhanced authentication mechanism to verify strongly each network entity to so]ye user authentication problem and support anonymity for user privacy.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1465-1468
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• 2008

모바일 에드혹 네트워크(MANET)에서 익명 라우팅을 위해 각 노드가 익명ID를 이용하여 MAC 단에서 익명으로 서로를 인증하고 네트워크 단에서 익명 라우팅 수행하는 AODV 기반의 라우팅 기법이 제안된바 있다[4]. 하지만 기존의 제안된 방법은 익명ID가 변경될 때마다 페어링 연산을 통해 재인증을 해야 하며, 라우팅 경로 중간의 노드들은 메시지의 연결성을 없에게 위해 매홉마다 암·복호화를 반복하여 상당히 비효율적이다. 본 논문은 기존논문의 노드 인증 기법을 확장하여 실제 메시지의 교환과정에서 일어나는 홉 간 암호화 횟수를 줄이고, 임시 인증값을 이용한 노드 상호간의 빠른 인증 기법을 사용하여 노드간의 인증과 익명성을 보장하는 보다 효율적인 프로토콜을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1102-1103
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• 2007

적대적이고 급변하는 애드혹 네트워크에서 각 노드들은 항상 적대적인 공격자들로부터 위조나 변조의 공격을 받을 수 있어서 통신 내용과 경로의 보안성이 필요하다. AnonDSR 기법은 보안성을 유지하면서 익명성을 효율적으로 보장하는 것으로 알려져 있지만 기존 기법에 비해 암호키를 설립하는 추가적인 절차를 수행하므로 통신 수행시간이 길어지는 문제가 발생한다. 제안 기법에서는 암호키 설립 단계와 통신경로를 설정하는 단계를 동시 수행하고 데이터 전송시에는 공유키로 암호화를 추가적으로 수행해서 보안 강도를 높인다. 결과적으로 제안기법은 AnonDSR 에 비해 매번 통신 수행시간이 최대 31% 향상되고 보안성도 강화된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.75-81
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• 2005

The GNUnet in P2P system have solved an anonymous(publisher, storer, demander); a service of condition equal for peer. The GNUnet for an anonymous has separated a file and dispersed to the network. But, the 1Kbyte block size of the GNUnet is a creation of many additional block. I and R block has created with indirect point of D block The waste of I and R block appeared to 4% of the original file and the additional network traffic for the block transmission. To resolve the problems, this paper proposes an new scheme of file splitting distribution using P2P networks with the new GNUnet protocol, The GNUnet support minimization of the additional block and for a network traffic. It proposed an efficiency improvement of encording block and routing algorithm.

• Journal of the HCI Society of Korea
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• v.12 no.2
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• pp.13-19
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• 2017

Various life-logging based on cloud service have developed social network according to the advanced technology of smartphone and wearable device. Daily digital life on social networks has been shared information and emotion and developed new social relationships. Recent life-logging has required social relationships beyond extension of personal memory and anonymity for privacy protection. This study is to determine social network group by using life-logging data obtained in daily lives and to categorize emotion behavior with anonymity guarantee. Social network group was defined by grouping similar representative emotional behavior. The public's patterns and trends was able to be inferred by analyzing representative emotion and behavior of the social groups network.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.12
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• pp.533-540
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• 2013

Anonymity is the one of main reasons for substantial improvement of Internet. It encourages various users to express their opinion freely and helps Internet based distributed systems vitalize. But, anonymity can cause unexpected threats because personal information of an online user is hidden. Especially, distributed systems are threatened by Sybil attack, where one malicious user creates and manages multiple fake online identities. To prevent Sybil attack, the traditional solutions include increasing the complexity of identity generation and mapping online identities to real-world identities. But, even though the high complexity of identity generation increases the generation cost of Sybil identities, eventually they are generated and there is no further way to suppress their activity. Also, the mapping between online identities and real identities may cause high possibility of losing anonymity. Recently, some methods using online social network to prevent Sybil attack are researched. In this paper, a new method is proposed for extracting a user's system-wide Sybil-resistant trust value by using the properties embedded in online social network graphs. The proposed method can be categorized into 3 types based on sampling and decision strategies. By using graphs sampled from Facebook, the performance of the 3 types of the proposed method is evaluated. Moreover, the impact of Sybil attack on nodes with different characteristics is evaluated in order to understand the behavior of Sybil attack.

• Journal of Digital Convergence
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• v.18 no.9
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• pp.57-62
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• 2020

Smart home based on Internet of things (IoT) is rapidly emerging as an exciting research and industry field. However, security and privacy have been critical issues due to the open feature of wireless communication channel. As a step towards this direction, Shuai et al. proposed an anonymous authentication scheme for smart home environment using Elliptic curve cryptosystem. They provided formal proof and heuristic analysis and argued that their scheme is secure against various attacks including de-synchronization attack, mobile device loss attack and so on, and provides user anonymity and untraceability. However, this paper shows that Shuai et al.'s scheme does not provide user anonymity nor untraceability, which are very important features for the contemporary IoT network environment.

• Journal of Internet Computing and Services
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• v.8 no.4
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• pp.93-103
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• 2007

Networking environments are exposed to outside attacks and privacy threats. Due to broadcast nature of radio transmissions, wireless devices experience more vulnerable situations than those of wired network devices. This paper assumes that a wireless device has two network interfaces, one for accessing internet using 3G services, and the other for constructing an ad hoc network. To deal with privacy threats, this paper introduces an approach in which wireless devices form a special ad hoc network in order to exchange data using anonymous communications. One or more intermediate peers should be involved in the construction of an anonymous path. The proposed anonymous communication mechanism discourages traffic analysis and improves user privacy. According to simulation results, the anonymous connection in an ad hoc network prefers the intermediate peer(s) which is located near the source and/or the destination peer, rather than randomly-selected peers.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.351-353
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• 2015

공공정보 공유 및 개방, 소셜네트워크서비스의 활성화 그리고 사용자 간의 공유 데이터 증가 등의 이유로 인터넷상에 노출되는 사용자의 개인 정보가 증가하고 있다. 인터넷상에 노출된 사용자들의 개인정보들은 연결공격(linkage attack), 배경지식 공격(background attack)으로 프라이버시를 침해할 수 있다. 이를 막기 위해 관계형 데이터베이스에서는 대표적으로 k-익명성(k-anonymity)을 시작으로 l-다양성(l-diversity), t-밀집성(t-closeness)이라는 익명화 모델이 제안되었으며 계속해서 익명화 알고리즘의 성능은 개선되고 있다. 하지만 k-익명성, l-다양성, t-밀집성 모델의 조건을 만족하기 위해서는 준식별자(quasi-identifier)를 일반화(generalization)처리 해주어야 하는데 이 과정에서 준식별자의 가치를 손실된다는 단점이 있다. 본 논문에서 준식별자의 정보 손실을 최소화하기 위해 k-익명성 모델을 만족시키는 과정에서 일반화와 데이터를 삽입을 사용하는 익명화 처리하는 방법을 제안한다.