• Annual Conference of KIPS
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• 2001.04a
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• pp.355-358
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• 2001

컴퓨터와 인터넷의 발전을 통하여 실생활에서 이루어지는 많은 일들이 가상공간에서 실현 가능하게 되었다. 그러나 이러한 가상공간을 활용함에 있어서 고려할 사항은 시스템 접속 요구자의 정당성을 확인하는 식별 및 인증 과정이다. 이러한 고려사항을 해결하기 위해서 많은 일회용 패스워드 방식이 제안되었다. 기존에 제안된 방식들은 도청이나 재시도 공격에는 안전하나 man-in-the-middle attack이나 서버 위장 공격에 취약점을 드러내고 있다. 본 논문에서는 기존의 일회용 패스워드 기술들 중 대표적인 방식들을 알아보고, 이에 대한 문제점을 도출한다. 그리고 일회용 패스워드 기술의 일반적인 고려사항과 기존에 제안된 방식들의 문제점들을 해결할 수 있는 새로운 일회용 패스워드 방식을 제안한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1519-1534
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• 2017

Data de-identification is the one of the technique that preserves individual data privacy and provides useful information of data to the analyst. However, original de-identification techniques like k-anonymity have vulnerabilities to background knowledge attacks. On the contrary, differential privacy has a lot of researches and studies within several years because it has both strong privacy preserving and useful utility. In this paper, we analyze various models based on differential privacy and formalize a differentially private model on financial data. As a result, we can formalize a differentially private model on financial data and show that it has both security guarantees and good usefulness.

• Convergence Security Journal
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• v.19 no.2
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• pp.113-121
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• 2019

With the development of the Internet and Information Communication Technology, there has been an increase in the amount of Open Source Intelligence(OSINT). OSINT can be highly effective, if well refined and utilized. Recently, it has been assumed that almost 95% of all information comes from public sources and the utilization of open sources has sharply increased. The ISVG and START programs, for example, collect information about open sources related to terrorism or crime, effectively used to detect terrorists and prevent crime. The open source information related to the cyber attacks is, however, quite different from that in terrorism (or crime) in that it is difficult to clearly identify the attacker, the purpose of attack, and the range of damage. In addition, the data itself of cyber attacks is relatively unstructured. So, a totally new approach is required to establish and utilize an OSINT database for cyber attacks, which is proposed in this paper.

• Journal of Korea Multimedia Society
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• v.16 no.12
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• pp.1413-1426
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• 2013

RFID thecnology has been widely adopted by industries for supply chain management. When a product item is manufactured RFID tag is attached to the product item and supply chain management among factories, distributors, retailers and customers needs to handle ownership transfer for the product item carefully. With RFID technology, the secure and efficient ownership transfer protocol is an important issue for the identification of product items and the overall system efficiency on supply chain. Many ownership transfer protocols have been proposed now. They have security problems and use complex operations such as encryption operation and hash function. Lo et al. proposed a protocol using lightweight operations such as shift, addition, XOR, and random number generation[1]. However, this protocol has a security problem in which the secret key between the tag and the new owner is disclosed to the attackers, and it is also weak against the Fraud attack[2]. In this paper, we propose a new ownership transfer protocol using lightweight operations such as shift, addition, and random number generation. This protocol is the modified version of Lo et al.'s protocol and is secure against the security attacks.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.3
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• pp.565-573
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• 2022

Current mobile communication system is in the mid-process of conversion from 4G LTE to 5G network. According to the generalization of mobile communication services, personal information such as user's identifiers and location information is transmitted through a mobile communication network. The importance of security technology is growing according to the characteristics of wireless mobile communication networks, the use of wireless shared channels is inevitable, and security technology cannot be applied to all network system elements in order to satisfy the bandwidth and speed requirements. In particular, for security threat analysis, researches are being conducted on various attack types and vulnerability analysis through rogue base stations or attacker UE to make user services impossible in the case of 5G networks. In this paper, we established a 5G network testbed using open sources. And we analyzed three security vulnerabilities related to NAS COUNT and confirmed the validity of two vulnerabilities based on the testbed or analyzing the 3GPP standard.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.481-483
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• 2004

NIDS(Network Intrusion Detection System)는 공격 탐지 과정에서 대량의 로그가 발생하게 되는데 일반적인 침입탐지 시스템에서 탐지되어 하루에 남는 로그만으로도 시스템에 막대한 양을 차지한다 이러한 문제점은 관리자에게 많은 부담을 줄뿐만 아니라 그렇게 남겨진 로그에는 오탐율(False Positive) 비율이 높기 때문에 관리자가 실제로 위협적인 침입을 식별하고, 침입 행위에 대한 빠른 대응을 어렵게 만든다. 그러므로 NIDS와 특정 호스트가 가지고 있는 보안상 취약한 부분을 비교하여 판단할 수 있는 침입탐지시스템을 선택, 운용하는 것은 관리측면이나 대응측면에서 매우 중요한 일이라고 할 수 있다. 본 논문에서는 NIDS와 해당 호스트 취약점 정보를 이용해 작성된 데이터베이스(HVIDB : Host Vulnerability Information Database)를 이용하여 호스트의 취약성에 관한 로그만을 최종 경고해줌으로써 오탐율의 양을 감소시키고 호스트 보안성의 향상과 관리자가 로그분석 등의 IDS 업무를 효과적으로 할 수 있는 모델을 제시한다.

• Convergence Security Journal
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• v.18 no.4
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• pp.3-10
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• 2018

Each online user should perform a separate registration and manage his ID and password for each online commerce or SNS service. Since a common secret is shared between the user and the SNS server, the server compromise induces the user privacy breach and financial loss. In this paper, it is considered that the user's authentication material is shared between multiple SNS servers for user authentication. A blockchain service architecture based on Hyperledger Fabric is proposed for each user to utilize an identical ID and OTP using the enhanced hash-chain-based OTP.

• Annual Conference of KIPS
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• 2007.11a
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• pp.1151-1153
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• 2007

P2P 및 Mobile Network, Reputations System 등의 분산 시스템은 sybil attack 에 노출되어 있다. sybil attack 은 한 명의 사용자가 다수의 식별자를 가진 것으로 위장하여 시스템 내에서 마치 실제 다수의 사용자인 양 시스템을 악용하는 공격방법이다. sybil attack 을 막기 위한 다양한 노력이 진행되었고, 최근에 SybilGuard 라는 social network 를 이용한 방어 방법이 제시되었다. SybilGuard 는 악의적인 사용자를 막기 위하여, Random Walk 의 변형이면서 결정적인 경로의 특징을 가지는 임의경로(Random Route)를 사용하여 악의적인 사용자의 sybil attack 을 방어한다. SybilGuard 는 sybil node 의 개수를 제한하고, 이들을 하나의 동일한 그룹으로 분류할 수 있도록 하여 시스템 내에서 가짜 식별자의 개수를 제한한다. 이를 위해 각 노드가 시스템에 돌어올 때 Verifier(V)노드가 이들 노드를 확인하게 되는데, 이를 위해 시스템 내의 선한 노드(Honest Node)를 사용하여 이들을 확인한다. 이 때, honest node 들은 verifier 의 요청에 따라 확인요청을 수행하게 되는데, social network 의 특성상 몇몇 노드들은 사회적인 명망으로 매우 큰 링크수를 가지게 될 것이며, 따라서 이들 노드들이 처리해야할 요청의 양이 매우 많아지게 될 것이다. 따라서 이들 honest node 들 간에 로드분포를 균등하게 하는 것이 요구되며, 이 논문에서는 부하 조절을 하기 위한 기법을 제시하고, 이들을 평가한다.

• KIISE Transactions on Computing Practices
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• v.22 no.8
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• pp.345-350
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• 2016

Cloud computing services have different characteristics from the traditional computing environment such as resource sharing, virtualization, etc. These characteristics of cloud computing environment necessitate specific properties such as user identify, access control, security control property, etc. Recently, Yoo proposed an attribute-based authentication scheme for secure cloud computing. However, Yoo's authentication scheme is vulnerable to customer attack and an adversary can modify the authentication request message. In this paper, we propose a secure and efficient attribute-based authentication scheme for cloud computing based on Yoo's scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.1
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• pp.57-67
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• 2013

Lately, intrusive incidents (including system hacking, viruses, worms, homepage alterations, and data leaks) have not involved the distribution of an virus or worm, but have been designed to acquire private information or trade secrets. Because an attacker uses advanced intelligence and attack techniques that conceal and alter data in a computer, the collector cannot trace the digital evidence of the attack. In an initial incident response first responser deals with the suspect or crime scene data that needs investigative leads quickly, in accordance with forensic process methodology that provides the identification of digital evidence in a systematic approach. In order to an effective initial response to first responders, this paper analyzes the collection data such as user usage profiles, chronology timeline, and internet data according to CFFPM(computer forensics field triage process model), proceeds to design, and implements a collection application to deploy the client/server architecture on the Windows based computer.