• KDI Journal of Economic Policy
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• v.38 no.2
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• pp.45-62
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• 2016

This paper analyzes changes in the export potential and competitiveness of China, Japan, and Korea. The analysis of Japan's export market share reveals that in sectors where Korea's potential was strong in the early 1990s, Japan's market share diminished. This suggests the possibility that Korea was catching up with Japan, eating into Japan's market share. The same analysis of Korea's export market share in the 2000s shows, for items in which China's export potential was high, Korea's market share has declined comparatively since 2010, with the tendency growing much larger. China's export potential continues to expand in markets for Korea's key export products, making it difficult to rule out the possibility that Korea's competitiveness in key export products will be hindered, driven by the catching up of China. To respond to these challenges, it is important for Korea continuously to foster and enhance creative and core capabilities that latecomers will not easily be able to emulate.

• Journal of Internet Computing and Services
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• v.7 no.3
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• pp.133-142
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• 2006

The purpose of the multiple key agreement protocol is to get efficiency in computational and communicational aspects compared to multiple executions of single key agreement protocol. However ID based tripartite multiple key agreement protocols have been proposed, it is reported that they can not resist unknown key-share attack or impersonation attack. How to design a secure and efficient ID-based authenticated tripartite multiple key agreement scheme to prevent all kinds of attacks remains an open problem. This paper proposes a multiple key agreement scheme combing the existing single key agreement protocol with a key derivation function. The proposed scheme can not only increase computational efficiency compared to the existing multiple key agreement protocol, but can ensure security of the proposed schemes by using a security proofed single key agreement protocol and key derivation function.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.4
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• pp.476-482
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• 2009

As a result from Hasse's theorem it is not always possible to share a common key between any two ECC public keys. Even though ECC algorithm is more efficient than any other Encryption's with respect to the encryption strength per bit, ECC ElGamal algorithm can not be used to distribute a common key to ECC PKI owners. Approaching mathematical ways in a practical situation, we suggest possible conditions to share a common key with ECC PKI's. Using computer experiments, we also show that these suggestions are right. In the conditions, we can distribute a common key to proper peoples with ECC ElGamal algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.2
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• pp.751-765
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• 2012

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.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.1
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• pp.3-10
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• 2002

This paper proposes an ID-based entity-aunthentication and authenticated key exchange protocol with ECC via two-pass communications between two parties who airs registered to the trusted third-party KC in advance. The proposed protocol developed by applying ECDSA and Diffie-Hellman key exchange scheme to the ID-based key distribution scheme over ECC proposed by H. Sakazaki, E. Okamoto and M. Mambo(SOM scheme). The security of this protocol is based on the Elliptic Curve Discrete Logarithm Problem(ECDLP) and the Elliptic Curve Diffie-Hellman Problem(ECDHP). It is strong against unknown key share attack and it provides the perfect forward secrecy, which makes up for the weakness in SOM scheme,

• The Journal of the Korea Contents Association
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• v.9 no.9
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• pp.105-113
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• 2009

The previous key management methods are not appropriate for secure data communication in cluster-based routing scheme. Because cluster heads are elected in every round and communicate with the member nodes for authentication and share-key establishment phase in the cluster. In addition, there are not considered to mobility of nodes in previous key management mechanisms. In this paper, we propose the secure and effective key management mechanisim in the cluster-based routing scheme that if there are no share keys between cluster head and its nodes, we create the cluster key using authentication with base station or trust autentication and exchange the their information for a round.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.5
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• pp.863-874
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• 2021

Distributed key generation (DKG) with trustless setup is a cryptographic protocol that distributes Shamir secret shares of a private key to participants while keeping the actual private key hidden to the participants. Also, by extending it to a threshold signature protocol, digital signatures can be generated without construction of private keys. This paper proposes a recovery protocol maintaining trustless setup assumptions, in particular to the useful (1,3) share structure. The proposed protocol meets same levels of security requirements with DKG in terms of correctness and secrecy. The protocol can also enable delegation and revocation of digital sign rights for blockchain-based asset management.

• Journal of Industrial Technology
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• v.24 no.B
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• pp.193-198
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• 2004

We propose and analyse a flexible secure file sharing scheme which can be used for data sharing among members in P2P environment. When a member wants to share data, notification messages are sent to the members with whom the member wants to share data. Each notification message includes one-time password encrypted with the receiver's public key. A member who received the notification message can download the data by using the one-time password. The proposed scheme provides selective sharing, download confirmation and efficient memory management. In terms of security, the proposed scheme supports authentication, entity privacy, replay attack protection and disguise prevention.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4552-4567
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• 2014

A (n,t,n) secret sharing scheme is to share a secret among n group members, where each member also plays a role of a dealer,and any t shares can be used to recover the secret. In this paper, we propose a strong (k,t,n) verifiable multi-secret sharing scheme, where any k out of n participants operate as dealers. The scheme realizes both threshold structure and adversary structure simultaneously, and removes a trusted third party. The secret reconstruction phase is performed using an additive homomorphism for decreasing the storage cost. Meanwhile, the scheme achieves the pre-verification property in the sense that any participant doesn't need to reveal any information about real master shares in the verification phase. We compare our proposal with the previous (n,t,n) secret sharing schemes from the perspectives of what kinds of access structures they achieve, what kinds of functionalities they support and whether heavy storage cost for secret share is required. Then it shows that our scheme takes the following advantages: (a) realizing the adversary structure, (b) allowing any k out of n participants to operate as dealers, (c) small sized secret share. Moreover, our proposed scheme is a favorable candidate to be used in many applications, such as secure multi-party computation and privacy preserving data mining, etc.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.2
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• pp.25-36
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• 1999

In this paper we propose a one-time password mechanism that solves the problems of the S/KEY: the limitation of a usage and the need of storage for keys. because of using a cryptographic algorithm the proposed mechanism has no the limitation of a usage. Also because of producing the key for an authentication from a user's password it is easy to manage the authentication key and is possible to share the session key between a client and a server after the authentication process. In addition the proposed mechanism is easy to protect and manage the authentication information because of using a smart card and is adopted by the system that needs a noe-way authentication from a client to a server without the challenge of a server.