• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권12호
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• pp.3352-3365
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• 2012

Group key agreement (GKA) is a cryptographic primitive allowing two or more users to negotiate a shared session key over public networks. Wu et al. recently introduced the concept of asymmetric GKA that allows a group of users to negotiate a common public key, while each user only needs to hold his/her respective private key. However, Wu et al.'s protocol can not resist active attacks, such as fabrication. To solve this problem, Zhang et al. proposed an authenticated asymmetric GKA protocol, where each user is authenticated during the negotiation process, so it can resist active attacks. Whereas, Zhang et al.'s protocol needs a partially trusted certificate authority to issue certificates, which brings a heavy certificate management burden. To eliminate such cost, Zhang et al. constructed another protocol in identity-based setting. Unfortunately, it suffers from the so-called key escrow problem. In this paper, we propose the certificateless authenticated asymmetric group key agreement protocol which does not have certificate management burden and key escrow problem. Besides, our protocol achieves known-key security, unknown key-share security, key-compromise impersonation security, and key control security. Our simulation based on the pairing-based cryptography (PBC) library shows that this protocol is efficient and practical.

• ETRI Journal
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• 제45권6호
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• pp.1090-1102
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• 2023

Authenticated multiple key agreement (AMKA) protocols provide participants with multiple session keys after one round of authentication. Many schemes use Diffie-Hellman or authenticated key agreement schemes that rely on hard integer factorizations that are vulnerable to quantum algorithms. Lattice cryptography provides quantum resistance to authenticated key agreement protocols, but the certificate always incurs excessive public key infrastructure management overhead. Thus, a lightweight lattice-based secure system is needed that removes this overhead. To answer this need, we provide a two-party lattice- and identity-based AMKA scheme based on bilateral short integer or computational bilateral inhomogeneous small integer solutions, and we provide a security proof based on the random oracle model. Compared with existing AMKA protocols, our new protocol has higher efficiency and stronger security.

• 인터넷정보학회논문지
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• 제6권5호
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• pp.27-43
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• 2005

EAP(Extenwsible Authentication Protocol)는 IEEE Std 802.1x 무선 근거리 통신망 및 RADIUS/DIAMETER 프로토콜을 기반으로 각 개체에 대한 인증을 제공하며 인증의 수단으로 인증서, 패스워드, 이중방식(패스워드 및 토큰)등을 이용한다. 인증된 키교환을 위한 패스워드 기반 인증 방식은 특정 하드웨어 장치 없이도 암기하기 쉬운 간편성, 편리성, 이동성으로 인해 상당히 많이 이용되는 사용자 인증 방식이다. 본 논문에서는 개방형 네트워크를 통해서도 사용자를 인증하고 안전한 암호통신용 세션키 교환에 적합한 패스워드 기반 인증된 키교환 프로토콜 SPAKE(Split Password-based Authenticated Key Exchange)을 제안한다. 더불어 제안된 SPAKE를 토대로 안전한 EAP 인증 프레임워크 EAP-SPAKE를 제시한다.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2005년도 춘계 종합학술대회 논문집
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• pp.91-96
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• 2005

최근 Personal Area Network (PAN)에서 신뢰성 있고 인증된 서비스를 제공하기 위하여 Personal Public Key Infrastructure (PKI)가 소개되었다. 그러나, PAN을 구성하는 대다수의 모바일 디바이스들은 일반적으로 제한된 컴퓨팅 능력을 가지므로, 기존PKI에서 사용되는 공개키 서명 기법과 CRL등의 인증서 상태 검증 기법 같이 많은 오버헤드를 요구하는 기법들은 적합하지 않다. 본 논문에서는 PAN을 구성하는 모바일 디바이스들을 위한 효율적인 서명 생성과 인증서 상태 검증을 지원하는 새로운 기법을 제안한다. 제안 기법은 해쉬체인 기법을 사용함으로써 전자서명 생성시 모바일 디바이스의 계산상 오버헤드를 감소시킬 수 있으며 또한, 인증서 상태 검증을 위한 통신상의 오버헤드를 감소시킬 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권3호
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• pp.1157-1177
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• 2014

Convertible authenticated encryption (CAE) schemes enable the signer to send a confidential message and its corresponding signature to the designated recipient. The recipient can also convert the signature into a conventional one which can be verified by anyone. Integrating the properties of self-certified public key systems, this paper presents efficient and computationally indistinguishable self-certified CAE schemes for strengthening the security of E-Commerce applications. Additionally, we also adapt the proposed schemes to elliptic curve systems for facilitating the applications of limited computing power and insufficient storage space. The proposed schemes are secure against known existential active attacks, satisfy the semantic security requirement, and have the following advantages: (i) No extra certificate is required since the tasks of authenticating the public key and verifying the signature can be simultaneously carried out within one step, which helps reducing computation efforts and communication overheads. (ii) In case of a later dispute, the recipient can convert the signature into an ordinary one for the public arbitration. (iii) The signature conversion can be solely performed by the recipient without additional computation efforts or communication overheads. (iv) The recipient of the signature can prove himself, if needed, to anyone that he is actually the designated recipient.

• 한국정보통신학회논문지
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• 제12권4호
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• pp.651-660
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• 2008

현재 인터넷과 같이 널리 사용되는 공개된 네트워크를 통해 법률적으로 유효한 문서나 상거래 계약서와 같은 엄격한 보안이 요구되는 기밀정보가 교환되고 있으며, 이와 동시에 이러한 기밀정보의 교환에 있어서 정보의 무결성과 인증을 위해 공개키 인증서가 사용되고 있다. 그러나 현 공개키 기반구조 환경에서는 공개키 인증서의 유효성을 확인하는데 있어서 전송용량 면이나 안전성면에서 여러 가지 문제점들을 내포하고 있다. 본 논문은 RSA 일방향 어큐뮬레이터를 사용하여 믿을 수 있는 정보제공자에 의해 유지되는 집합에 대한 사용자의 멤버쉽 질의에 대해 공모 가능한 디렉토리가 암호학적으로 검증된 응답을 제공하는 효율적이고 동적인 인증된 딕셔너리를 실현하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권5호
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• pp.1687-1707
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• 2022

With the development of multiuser online meetings, more group-oriented technologies and applications for instance collaborative work are becoming increasingly important. Authenticated Group Key Agreement (AGKA) schemes provide a shared group key for users with after their identities are confirmed to guarantee the confidentiality and integrity of group communications. On the basis of the Public Key Cryptography (PKC) system used, AGKA can be classified as Public Key Infrastructure-based, Identity-based, and Certificateless. Because the latter type can solve the certificate management overhead and the key escrow problems of the first two types, Certificateless-AGKA (CL-AGKA) protocols have become a popular area of research. However, most CL-AGKA protocols are vulnerable to Public Key Replacement Attacks (PKRA) due to the lack of public key authentication. In the present work, we present a CL-AGKA scheme that can resist PKRA in order to solve impersonation attacks caused by those attacks. Beyond security, improving scheme efficiency is another direction for AGKA research. To reduce the communication and computation cost, we present a scheme with only one round of information interaction and construct a CL-AGKA scheme replacing the bilinear pairing with elliptic curve cryptography. Therefore, our scheme has good applicability to communication environments with limited bandwidth and computing capabilities.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권6호
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• pp.3299-3315
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• 2019

Deniable authentication (DA) is a protocol in which a receiver can generate an authenticator that is probabilistically indistinguishable from a sender. DA can be applied in many scenarios that require user privacy protection. To enhance the security of DA, in this paper, we construct a new deniable authenticated encryption (DAE) scheme that realizes deniable authentication and confidentiality in a logical single step. Compared with existing approaches, our approach provides proof of security and is efficient in terms of performance analysis. Our scheme is in an identity-based environment; thus, it avoids the public key certificate-based public key infrastructure (PKI). Moreover, we provide an example that shows that our protocol is applicable for e-voting systems.

• IEIE Transactions on Smart Processing and Computing
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• 제3권5호
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• pp.298-305
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• 2014

In this study, a novel Randomly Shifted Certification Authority Authentication protocol was used in ad hoc networks to provide authentication by considering the MAC layer characteristics. The nodes achieve authentication through the use of public key certificates issued by a CA, which assures the certificate's ownership. As a part of providing key management, the active CA node transfers the image of the stored public keys to other idle CA nodes. Finally the current active CA randomly selects the ID of the available idle CA and shifts the CA ownership by transferring it. Revoking is done if any counterfeit or duplicate non CA node ID is found. Authentication and integrity is provided by preventing MAC control packets, and Enhanced Hash Message Authentication Code (EHMAC) can be used. Here EHMAC with various outputs is introduced in all control packets. When a node transmits a packet to a node with EHMAC, verification is conducted and the node replies with the transmitter address and EHMAC in the acknowledgement.

• International Journal of Internet, Broadcasting and Communication
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• 제8권2호
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• pp.38-42
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• 2016

In this paper, we propose 3-factor mobile banking authentication scheme applied to face recognition techniques with existing certificate and OTP. An image of the user's face is captured by smart phone camera and its brightness processing of the contour of a face and background by n of X and Y points. Then, distance between the point of eyes, nose and mouth from captured user's face are compared with stored facial features. When the compared results corresponding to the data that stored in a face recognition DB, the user is authenticated.