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유료 방송 시스템에 적합한 ID 기반의 2 라운드 그룹키 동의 프로토콜
김현주(Hyunjue Kim),남정현(Junghyun Nam),김승주(Seungjoo Kim),원동호(Dongho Won) 한국정보보호학회 2005 정보보호학회논문지 Vol.14 No.1
그룹키 동의 프로토콜은 일련의 그룹을 형성하는 다수의 통신 참여자들이 공개된 통신망을 통해 안전하고 효율적인 방법으로 그룹의 세션키를 설정하기 위한 목적으로 설계된다. 본 논문에서는 유료 방송 시스템과 같은 그룹중심의 응용이나 서비스에 적합한 ID 기반의 2 라운드의 그룹키 동의 프로토콜을 제안하고, 이의 안전성을 CDH 가정과 BDDH 가정에 기반하여 랜덤 오라클 모델에서 증명한다. 제안하는 프로토콜은 Nam이 제안한 3 라운드 그룹키 동의 프로토콜을 기초로 설계된 것으로, 개인식별정보에 기반한 암호 시스템을 사용하여 키 관리 절차를 보다 간단히 하였으며, 새로운 인증 메카니즘을 사용하여 키 전송 메시지들의 길이를 줄이고 결합적 단순성을 제공하였다. 또한 제안하는 프로토콜은 전송되는 메시지들에 대한 인증을 묶음(batch) 기법을 사용하여 검증하도록 설계하여 효율성을 더욱 개선시켰다. A group key agreement protocol allows a group of users to share a key which may later be used to achieve certain cryptographic goals. In this paper, we propose a new scalable two-round ID-based group key agreement protocol which would be well fit to a Pay-TV system, additionally, to the fields of internet stock quotes, audio and music deliveries, software updates and the like. Our protocol improves the three round group key agreement protocol of Nam et al., resulting in upgrading the computational efficiency by using the batch verification technique in pairing-based cryptography. Also our protocol simplifies the key agreement procedures by utilizing ID-based system. We prove the security of our protocol under the Computational Diffie-Hellman assumption and the Bilinear Decisional Diffie-Hellman assumption. Also we analyze its efficiency.
Dictionary Attacks against Password-Based Authenticated Three-Party Key Exchange Protocols
( Junghyun Nam ),( Kim-kwang Raymond Choo ),( Moonseong Kim ),( Juryon Paik ),( Dongho Won ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.12
A three-party password-based authenticated key exchange (PAKE) protocol allows two clients registered with a trusted server to generate a common cryptographic key from their individual passwords shared only with the server. A key requirement for three-party PAKE protocols is to prevent an adversary from mounting a dictionary attack. This requirement must be met even when the adversary is a malicious (registered) client who can set up normal protocol sessions with other clients. This work revisits three existing three-party PAKE protocols, namely, Guo et al.`s (2008) protocol, Huang`s (2009) protocol, and Lee and Hwang`s (2010) protocol, and demonstrates that these protocols are not secure against offline and/or (undetectable) online dictionary attacks in the presence of a malicious client. The offline dictionary attack we present against Guo et al.`s protocol also applies to other similar protocols including Lee and Hwang`s protocol. We conclude with some suggestions on how to design a three-party PAKE protocol that is resistant against dictionary attacks
Security Weaknesses in Harn-Lin and Dutta-Barua Protocols for Group Key Establishment
( Junghyun Nam ),( Moonseong Kim ),( Juryon Paik ),( Dongho Won ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.2
Key establishment protocols are fundamental for establishing secure communication channels over public insecure networks. Security must be given the topmost priority in the design of a key establishment protocol. In this work, we provide a security analysis on two recent key establishment protocols: Harn and Lin`s group key transfer protocol and Dutta and Barua`s group key agreement protocol. Our analysis shows that both the Harn-Lin protocol and the Dutta-Barua protocol have a flaw in their design and can be easily attacked. The attack we mount on the Harn-Lin protocol is a replay attack whereby a malicious user can obtain the long-term secrets of any other users. The Dutta-Barua protocol is vulnerable to an unknown key-share attack. For each of the two protocols, we present how to eliminate their security vulnerabilities. We also improve Dutta and Barua`s proof of security to make it valid against unknown key share attacks.
On the Security of a Simple Three-Party Key Exchange Protocol without Server's Public Keys
Nam, Junghyun,Choo, Kim-Kwang Raymond,Park, Minkyu,Paik, Juryon,Won, Dongho Hindawi Publishing Corporation 2014 The Scientific World Journal Vol.2014 No.-
<P>Authenticated key exchange protocols are of fundamental importance in securing communications and are now extensively deployed for use in various real-world network applications. In this work, we reveal major previously unpublished security vulnerabilities in the password-based authenticated three-party key exchange protocol according to Lee and Hwang (2010): (1) the Lee-Hwang protocol is susceptible to a man-in-the-middle attack and thus fails to achieve implicit key authentication; (2) the protocol cannot protect clients' passwords against an offline dictionary attack; and (3) the indistinguishability-based security of the protocol can be easily broken even in the presence of a passive adversary. We also propose an improved password-based authenticated three-party key exchange protocol that addresses the security vulnerabilities identified in the Lee-Hwang protocol.</P>
Password-Only Authenticated Three-Party Key Exchange with Provable Security in the Standard Model
Nam, Junghyun,Choo, Kim-Kwang Raymond,Kim, Junghwan,Kang, Hyun-Kyu,Kim, Jinsoo,Paik, Juryon,Won, Dongho Hindawi Publishing Corporation 2014 The Scientific World Journal Vol.2014 No.-
<P>Protocols for password-only authenticated key exchange (PAKE) in the three-party setting allow two clients registered with the same authentication server to derive a common secret key from their individual password shared with the server. Existing three-party PAKE protocols were proven secure under the assumption of the existence of random oracles or in a model that does not consider insider attacks. Therefore, these protocols may turn out to be insecure when the random oracle is instantiated with a particular hash function or an insider attack is mounted against the partner client. The contribution of this paper is to present the first three-party PAKE protocol whose security is proven without any idealized assumptions in a model that captures insider attacks. The proof model we use is a variant of the indistinguishability-based model of Bellare, Pointcheval, and Rogaway (2000), which is one of the most widely accepted models for security analysis of password-based key exchange protocols. We demonstrated that our protocol achieves not only the typical indistinguishability-based security of session keys but also the password security against undetectable online dictionary attacks.</P>
A Provably-Anonymous Authentication Scheme for Roaming Services
Junghyun Nam,Kim-Kwang Raymond Choo,Juryon Paik 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.3
In this work, we extend the widely accepted security model of Bellare, Pointcheval and Rogaway (2000) in order to prove the security of smart-card-based roaming authentication (SRA) schemes. More specifically, in this extended model, we provide formal definitions of authenticated key exchange and user anonymity for SRA schemes, in order to capture side-channel, offline dictionary, and other common attacks. We then present a new SRA scheme and prove its security in our extended model. To the best of our knowledge, our proposed scheme is the first provably-secure SRA scheme that achieves user anonymity. We conclude by demonstrating that our scheme is also computationally efficient relative to other similar published schemes without a security proof.
Nam, Junghyun,Choo, Kim-Kwang Raymond,Paik, Juryon,Won, Dongho Hindawi Publishing Corporation 2014 The Scientific World Journal Vol.2014 No.-
<P>While a number of protocols for password-only authenticated key exchange (PAKE) in the 3-party setting have been proposed, it still remains a challenging task to prove the security of a 3-party PAKE protocol against insider dictionary attacks. To the best of our knowledge, there is no 3-party PAKE protocol that carries a formal proof, or even definition, of security against insider dictionary attacks. In this paper, we present the first 3-party PAKE protocol proven secure against both online and offline dictionary attacks as well as insider and outsider dictionary attacks. Our construct can be viewed as a protocol compiler that transforms any 2-party PAKE protocol into a 3-party PAKE protocol with 2 additional rounds of communication. We also present a simple and intuitive approach of formally modelling dictionary attacks in the password-only 3-party setting, which significantly reduces the complexity of proving the security of 3-party PAKE protocols against dictionary attacks. In addition, we investigate the security of the well-known 3-party PAKE protocol, called GPAKE, due to Abdalla et al. (2005, 2006), and demonstrate that the security of GPAKE against online dictionary attacks depends heavily on the composition of its two building blocks, namely a 2-party PAKE protocol and a 3-party key distribution protocol.</P>
Single Nucleotide Polymorphisms of Matrix Metalloproteinase in Koreans
Nam, JungHyun,Park, KyungSook 한국유전학회 2004 Genes & Genomics Vol.26 No.3
The matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases, which can promote cancer progression and are synthesized by the cancer, inflammatory and endothelial cells. Moreover, MMP promoter variants are known to modify the transcriptional effects of MMPs. In this study we investigated the MMP1, MMP3, MMP7, MMP12, and MMP9 single nucleotide polymorphisms and their haplotypes in MMP promoters in Koreans. The genotypes and allele frequencies of these five genes were compatible with the Hardy-Weinberg equilibrium. The allele frequencies of MMP1-1607^(*)GG, MMP3-1171^(*)6A, MMP7-181^(*)A, MMP12-82^(*)A, and MMP9-1562^(*)C were determined to be 0.714, 0.874, 0.945, 0.983, and 0.883, respectively, and the allele frequencies of the MMPI and MMP3 polymorphisms were found to depend on ethnicity. The frequency of MMP1-1607^(*)GG in Koreans (0.714) was found to be similar to that of other Orientals, to differ from those of Caucasians (0.504 - 0.527) and Blacks (0.526). The MMP3-1171^(*)6A allele was more frequent in Koreans (0.874) than in Caucasians (0.464 - 0.555), and the haplotype frequencies of the MMP7, MMP1, MMP3, and MMP12 were; MMP1-181^(*)A - MMP1-1607^(*)GG - MMP3-1171^(*)6A - MMP12-82^(*)A (0.601), MMP1-181^(*)A - MMP1-1607^(*)G - MMP3-I171^(*)6A - MMP12-82^(*)A (0.209), and others (0.19). Information on the transcriptional effects on SNPs and haplotypes on MMP promoter regions will be useful for identifying genetic marker in tumor invasion and metastasis, and in chronic inflammatory diseases etiologically associated with increased MMP expression.