• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권12호
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• pp.3338-3351
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• 2012

There is an intuitive connection between signcryption and key agreement. Such a connector may lead to a novel way to construct authenticated and efficient group key agreement protocols. In this paper, we present a primary approach for constructing an authenticated group key agreement protocol from signcryption. This approach introduces desired properties to group key agreement. What this means is that the signcryption gives assurance to a sender that the key is available only to the recipient, and assurance to the recipient that the key indeed comes from the sender. Following the generic construction, we instantiate a distributed two-round group key agreement protocol based on signcryption scheme given by Dent [8]. We also show that this concrete protocol is secure in the outsider unforgeability notion and the outsider confidentiality notion assuming hardness of the Gap Diffie-Hellman problem.

• ETRI Journal
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• 제34권3호
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• pp.482-484
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• 2012

With the rapid progress of wireless mobile communications, the authenticated key agreement (AKA) protocol has attracted an increasing amount of attention. However, due to the limitations of bandwidth and storage of the mobile devices, most of the existing AKA protocols are not suitable for wireless mobile communications. Recently, Lo and others presented an efficient AKA protocol based on elliptic curve cryptography and included their protocol in 3GPP2 specifications. However, in this letter, we point out that Lo and others' protocol is vulnerable to an offline password guessing attack. To resist the attack, we also propose an efficient countermeasure.

• 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.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2002년도 가을 학술발표논문집 Vol.29 No.2 (1)
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• pp.547-549
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• 2002

Seo와 Sweeny는 통신 당사자간의 직접적인 세션키(session key) 교환을 위해 SAKA(Simple Authenticated Key Agreement Algorithm)를 제안했다. SAKA는 패스워드(password)를 사용하여 사용자인증 기능을 제공하는 변형된 Diffie-Hellman 키 교환 프로토콜로써, 키 생성 및 사용자 인증 시 요구되는 계산량과 메시지 전송량을 고려할 때 효율적인 프로토콜이다. 그러나, 최근에 Lin은 SAKA의 안전성에 취약점이 있음을 지적하고 개선된 프로토콜을 제안하였다. 본 논문에서는 개선된 프로토콜이 여전히 재전송 공격(replay attack)에 안전하지 않기 때문에 사용자 인증을 제공 할 수 없음을 보인다.

• 정보보호학회논문지
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• 제16권4호
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• pp.139-146
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• 2006

1997년 Yuliang Zheng에 의해 제안된 Signcryption은 서명과 암호 기법을 결합한 하이브리드 공개키 프리미티브로서 서명 기법 후 암호 기법을 각각 적용한 기법보다 계산 및 통신비용 측면에서 높은 효율성을 갖는 기법이다. 또한 PAK(Pass-word-Authenticated Key Exchange) 프로토콜은 사용자가 암기하거나 휴대하기 쉬운 짧은 길이의 패스워드를 기반으로 통신주체를 상호 인증하고, 결과적으로 안전한 통신을 위하여 충분히 큰 길이의 세션키를 분배하는 프로토콜이다. 본 논문에서는 PAK와 Signcryption의 특징을 이용하여 참여자의 비밀 정보를 이용한 상호 인증 및 안전한 통신을 위한 키 분배 프로토콜을 제안한다. 그리고 제안 프로토콜의 보안성을 증명하고 효율성을 비교한다.

• Journal of Communications and Networks
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• 제18권2호
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• pp.190-200
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• 2016

In this paper, we consider some aspects of binding properties that bind an anonymous user with messages. According to whether all the messages or some part of the messages are bound with an anonymous user, the protocol is said to satisfy the full binding property or the partial binding property, respectively. We propose methods to combine binding properties and anonymity-based authenticated key agreement protocols. Our protocol with the full binding property guarantees that while no participant's identity is revealed, a participant completes a key agreement protocol confirming that all the received messages came from the other participant. Our main idea is to use an anonymous signature scheme with a signer-controlled yet partially enforced linkability. Our protocols can be modified to provide additional properties, such as revocable anonymity. We formally prove that the constructed protocols are secure.

• 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.

• 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.

• 한국정보보호학회:학술대회논문집
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• 한국정보보호학회 2003년도 동계학술대회
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• pp.620-624
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• 2003

In［5］, the bit security of keys obtained from protocols based on pairings has been discussed. However it was not able to give bit security of tripartite authenticated key(TAK) agreement protocol of type 4. This paper shows the bit security of keys obtained from TAK-4 protocol.

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.340-344
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• 2009

Multi-server password authentication schemes enable remote users to obtain service from multiple servers with single password without separately registering to each server. In 2007, Hu-Niu-Yang proposed an improved efficient password authenticated key agreement scheme for multi-server architecture based on Chang-Lee's scheme proposed in 2004. This scheme is claimed to be more efficient and is able to overcome a few existing deficiencies in Chang-Lee's scheme. However, we find false claim of forward secrecy property and some potential threats such as offline dictionary attack, key-compromise attack, and poor reparability in their scheme. In this paper, we will discuss these issues in depth.