• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권5호
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• pp.1313-1327
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• 2013

How to make people keep both the confidentiality of the sensitive data and the privacy of their real identity in communication networks has been a hot topic in recent years. Researchers proposed privacy-preserving authenticated key exchange protocols (PPAKE) to answer this question. However, lots of PPAKE protocols need users to remember long secrets which are inconvenient for them. In this paper we propose a lightweight three-party privacy-preserving authentication key exchange (3PPAKE) protocol using smart card to address the problem. The advantages of the new 3PPAKE protocol are: 1. The only secrets that the users need to remember in the authentication are their short passwords; 2. Both of the users can negotiate a common key and keep their identity privacy, i.e., providing anonymity for both users in the communication; 3. It enjoys better performance in terms of computation cost and security. The security of the scheme is given in the random oracle model. To the best of our knowledge, the new protocol is the first provably secure authentication protocol which provides anonymity for both users in the three-party setting.

• 한국멀티미디어학회논문지
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• 제11권10호
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• pp.1403-1408
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• 2008

서버의 부담을 줄이기 위하여 스마트카드를 이용한 3자간 키 교환 프로토콜 방식과 패스워드 기반 2자간 키 교환 및 인증 프로토콜 방식들이 많이 제안되고 있다. 본 논문에서는 스마트 카드 기반 3자간 키 교환 및 인증 프로토콜 방식의 취약점에 대한 분석 및 검토를 행하였다. 또한, 심 경아 등에 의한 오프라인 패스워드 추측 공격에 취약점을 보인 곽 진 등의 방식을 분석하여 보고 이 공격에 대한 대책도 제시하고자 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권12호
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• pp.6188-6204
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• 2017

Over the years, more password-based authentication key agreement schemes using chaotic maps were susceptible to attack by off-line password guess attack. This work approaches this problem by a new method--new theorem of chaotic maps: $T_{a+b}(X)+T_{a-b}(X)=2T_a(X)T_b(X)$,(a>b). In fact, this method can be used to design two-party, three-party, even in N-party intelligently. For the sake of brevity and readability, only a two-party instance: a novel Two-party Password-Authenticated Key Agreement Protocol is proposed for resisting password guess attack in this work. Compared with the related literatures recently, our proposed scheme can be not only own high efficiency and unique functionality, but is also robust to various attacks and achieves perfect forward secrecy. For capturing improved ratio of security and efficiency intuitively, the paper firstly proposes a new parameter called security/efficiency ratio(S/E Ratio). The higher the value of the S/E Ratio, the better it is. Finally, we give the security proof and the efficiency analysis of our proposed scheme.

• 대한전자공학회논문지TC
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• 제40권4호
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• pp.22-29
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• 2003

개인 서비스 환경의 이동성과 전역 로밍을 위해 제안된 VHE(virtual home environment) 구조에서 가입자는 홈 망에서와 동일한 서비스를 방문 망에서도 제공받을 수 있게 된다. 가입자에게 서비스 이동성을 제공하기 위해서는 홈 망에 보관되어 있는 사용자 데이터와 서비스 로직이 방문 망으로 전달되어야 한다. 이 경우 사용자 프로파일과 서비스 로직은 보안에 민감한 정보를 포함하고 있으므로 통신의 신뢰성을 유지하기 위해서 모든 엔티티 사이의 상호 인증 절차가 요구된다. 이를 위해 본 논문에서 3G/4G 망의 VHE에 적용 가능한 3자간의 상호 인증 절차를 제안하고 분석한다.

• 디지털산업정보학회논문지
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• 제5권4호
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• pp.139-150
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• 2009

Authentication and key exchange are fundamental for establishing secure communication channels over public insecure networks. Password-based protocols for authenticated key exchange are designed to work even when user authentication is done via the use of passwords drawn from a small known set of values. There have been many protocols proposed over the years for password authenticated key exchange in the three-party scenario, in which two clients attempt to establish a secret key interacting with one same authentication server. However, little has been done for password authenticated key exchange in the more general and realistic four-party setting, where two clients trying to establish a secret key are registered with different authentication servers. In fact, the recent protocol by Yeh and Sun seems to be the only password authenticated key exchange protocol in the four-party setting. But, the Yeh-Sun protocol adopts the so called "hybrid model", in which each client needs not only to remember a password shared with the server but also to store and manage the server's public key. In some sense, this hybrid approach obviates the reason for considering password authenticated protocols in the first place; it is difficult for humans to securely manage long cryptographic keys. In this work, we introduce a key agreement protocol and a key distribution protocol, respectively, that requires each client only to remember a password shared with its authentication server.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제2권6호
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• pp.312-332
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• 2008

Password-based authentication key exchange (PAKE) protocols in the literature typically assume a password that is shared between a client and a server. PAKE has been applied in various environments, especially in the “client-server” applications of remotely accessed systems, such as e-banking. With the rapid developments in modern communication environments, such as ad-hoc networks and ubiquitous computing, it is customary to construct a secure peer-to-peer channel, which is quite a different paradigm from existing paradigms. In such a peer-to-peer channel, it would be much more common for users to not share a password with others. In this paper, we consider password-based authentication key exchange in the three-party setting, where two users do not share a password between themselves but only with one server. The users make a session-key by using their different passwords with the help of the server. We propose an efficient password-based authentication key exchange protocol with different passwords that achieves forward secrecy in the standard model. The protocol requires parties to only memorize human-memorable passwords; all other information that is necessary to run the protocol is made public. The protocol is also light-weighted, i.e., it requires only three rounds and four modular exponentiations per user. In fact, this amount of computation and the number of rounds are comparable to the most efficient password-based authentication key exchange protocol in the random-oracle model. The dispensation of random oracles in the protocol does not require the security of any expensive signature schemes or zero-knowlegde proofs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.5135-5149
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• 2015

Communications among multi-party must be fast, cost effective and secure. Today's computing environments such as internet conference, multi-user games and many more applications involve multi-party. All participants together establish a common session key to enable multi-party and secure exchange of messages. Multi-party password-based authenticated key exchange scheme allows users to communicate securely over an insecure network by using easy-to-remember password. Kwon et al. proposed a practical three-party password-based authenticated key exchange (3-PAKE) scheme to allow two users to establish a session key through a server without pre-sharing a password between users. However, Kwon et al.'s scheme cannot meet the security requirements of key authentication, key confirmation and anonymity. In this paper, we present a novel, simple and efficient multi-party password-based authenticated key exchange (M-PAKE) scheme based on the elliptic curve cryptography for mobile environment. Our proposed scheme only requires two round-messages. Furthermore, the proposed scheme not only satisfies security requirements for PAKE scheme but also achieves efficient computation and communication.

• 정보과학회 논문지
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• 제42권1호
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• pp.23-32
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• 2015

안드로이드 마켓을 보면 서드 파티 어플리케이션이 상당한 비중을 차지하는 것을 볼 수 있다. 하지만 이런 서드 파티 어플리케이션의 보안 측면에 대한 연구는 많이 이루어지지 않고 있는 실정이다. 그 중에서도 서드 파티 어플리케이션이 많이 사용되는 것 중 하나가 모바일 VoIP(Voice Over IP) 어플리케이션이다. 모바일 VoIP 어플리케이션 중에서 본 논문은 구글 보이스 서비스를 연동시켜주는 대표적인 3가지 서드 파티 어플리케이션의 사용자 인증 구조에 대해 알아본다. 그리고 안드로이드 파일 시스템 구조 속에서 사용자 계정 정보를 저장하고 있는 파일을 통해 계정 정보를 전달하는 흐름을 파악하고 현재 쓰이고 있는 방법에 대한 취약점을 통해 일어날 수 있는 위험 요소를 알아보고 타원 곡선 디피-헬만 키 교환과 해시 체이닝을 사용해 개선된 인증 메커니즘 방안을 제안한다.

• 정보보호학회논문지
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• 제16권6호
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• pp.73-80
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• 2006

최근 Sun등은 서버의 공개키를 사용하고 사용자의 패스워드로부터 유도된 검증자를 이용한 3자 참여 인증된 키교환 프로토콜을 제안하였다. 본 논문에서는 스마트카드를 사용한 패스워드 기반의 3자 참여 인증된 키교환 프로토콜을 제안한다. 제안된 프로토콜은 Sun등의 프로토콜에 비해 공개키 연산 대신 XOR과 해쉬함수 연산을 사용하기 때문에 계산비용이 매우 작으며, 또한 메시지 전송회수도 20% 줄어들기 때문에 효율적으로 인증된 키 교환을 수행할 수 있다. 또한, 제안된 기법에서는 패스워드를 서버에 저장하지 않으므로 패스워드 추측공격에 안전하고, 두 사용자들 간에 공유된 세션키를 서버가 알 수 없기 때문에 서버 Compromise 공격으로부터도 안전하다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권12호
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• pp.6169-6187
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• 2017

With the fast growth of mobile services, Mobile Cloud Computing(MCC) has gained a great deal of attention from researchers in the academic and industrial field. User authentication and privacy are significant issues in MCC environment. Recently, Tsai and Lo proposed a privacy-aware authentication scheme for distributed MCC services, which claimed to support mutual authentication and user anonymity. However, Irshad et.al. pointed out this scheme cannot achieve desired security goals and improved it. Unfortunately, this paper shall show that security features of Irshad et.al.'s scheme are achieved at the price of multiple time-consuming operations, such as three bilinear pairing operations, one map-to-point hash function operation, etc. Besides, it still suffers from two minor design flaws, including incapability of achieving three-factor security and no user revocation and re-registration. To address these issues, an enhanced and provably secure authentication scheme for distributed MCC services will be designed in this work. The proposed scheme can meet all desirable security requirements and is able to resist against various kinds of attacks. Moreover, compared with previously proposed schemes, the proposed scheme provides more security features while achieving lower computation and communication costs.