• Journal of KIISE:Software and Applications
• /
• v.32 no.12
• /
• pp.1238-1246
• /
• 2005

This thesis is written with web security module for safe data transmission between heterogeneous systems(ex. OS). Web system has allowed users to have great convenience and a lot of information. Though web service business has been progressed much, because of the limitation of it's own system, lots of loss, derived from data spillage which is the weakest point of security, has also followed. Suggested security module is realized by two module. One for server security module for web server, the other is client security module for client. The security structure, suggested on this thesis guarantee safe data transmission by only simple installation of modules in clients and servers. for speed sensitive transmission between web server and browser, Triple-DES, symmetric encryption system suitable for fast encryption communication, is adapted. To solve problems caused from key management, Diffie-Hellman's key exchange algorithm is adapted. By this method, all symmetric encryption troubles from key distribution and management, speed could be work out a solution. And Diffie-Hellman type algorithm secures Authentication for safe data Protection.

• Journal of KIISE:Information Networking
• /
• v.31 no.4
• /
• pp.353-362
• /
• 2004

Mobile Ad-Hoc network tends to expose scarce computing resources and various security threats because all traffics are carried in air along with no central management authority. To provide secure communication and save communication overhead, a scheme is inevitable to serurely establish session keys. However, most of key establishment methods for Ad-Hoc network focus on the distribution of a group key to all hosts and/or the efficient public key management. In this paper, a secure and efficient scheme is proposed to establish a session key between two Ad-Hoc nodes. The proposed scheme makes use of the secret sharing mechanism and the Diffie-Hellman key exchange method. For secure intra-cluster communication, each member node establishes session keys with its clusterhead, after mutual authentication using the secret shares. For inter-cluster communication, each node establishes session keys with its correspondent node using the public key and Diffie-Hellman key exchange method. The simulation results prove that the proposed scheme is more secure and efficient than that of the Clusterhead Authentication Based Method(1).

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.13 no.5
• /
• pp.147-157
• /
• 2003

We often use cryptographic systems on small devices such as mobile phones, smart cards and so on. But such devices are delicate against the tlreat of key exposure of secret keys. To reduce the damage caused by exposure of secret keys stored on such devices, the concept of forward security is introduced. In this Paper, we present a new forward secure signature scheme based on Gap Diffie-Hellman groups. Our scheme achieves security against chosen-message attacks under the computational Diffie-Hellman assumption in the random oracle model.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.13 no.5
• /
• pp.3-15
• /
• 2003

The secure group communication enables the members, which belong to the same group, to communicate each other in a secure and secret manner. To do so, it is the most important that a group key is securely distributed among them and also group membership is efficiently managed. In detail, the generation, the distribution and the refreshment of a group key would be highly regarded in terms of low communication and computation complexity. In this paper, we show you a new protocol to generate a group key which will be safely shared within a group, utilizing the 2-party Diffie-Hellman key exchange protocol and the complete binary tree. Our protocol has less complexity of computation per group member by substituting many parts of exponentiation computations for multiplications. Consequently, each group member needs constant computations of exponentiation and multiplication regardless of the group size in the protocol and then it has less complexity of the computation than that of any other protocols.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.9 no.2
• /
• pp.162-170
• /
• 2016

The key exchange protocols are very important to provide the secure communication in broadband satellite access network. However key exchange protocol of ETSI(European Telecommunications Standards Institute) is vulnerable to man-in-the-middle-attack by using Diffie-Hellman algorithm. And the key exchange protocol using certification is not useful in satellite environment. We propose the key exchange protocol using Timestamp which have the resistant to man-in-the-middle-attack. Proposed protocol is able to prevent the man-in-the-middle-attack by calculated time value. Also showing experiment results, we prove that proposed protocol improve memory usage, communication amount and calculation amount than other protocols.

• The KIPS Transactions:PartC
• /
• v.9C no.6
• /
• pp.799-808
• /
• 2002

According to the wide-spread of information transmission system over network, the use of cryptographic system to provide the integrity of transmitted message over network is increasing and the importance of that is emphasized. Because the security of the cryptographic system totally relies on the key, key management is a essential part of cryptographic system. A number of key agreement protocols have been proposed to far, but their rigorous security analysis is still open. In this paper, we analyze the features of Diffie-Hellman based standard key agreement protocols and provide the security analysis of those protocols against several kinds of active attacks.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.19 no.3
• /
• pp.73-82
• /
• 2009

This paper proposes an efficient and secure user authentication and key agreement scheme instead of the HTTP digest and TLS between the SIP UA and server. Although a number of security schemes for authentication and key exchange in SIP network are proposed, they still suffer from heavy computation overhead on the UA's side. The proposed scheme uses the HTIP Digest authentication and employs the Diffie-Hellman algorithm to protect user password against dictionary attacks. For a resource-constrained SIP UA, the proposed scheme delegates cryptographically computational operations like an exponentiation operation to the SIP server so that it is more efficient than the existing schemes in terms of energy consumption on the UA. Furthermore, it allows the proposed scheme to be easily applied to the deployed SIP networks since it does not require major modification to the signaling path associated with current SIP standard.

• Proceedings of the Korea Society for Industrial Systems Conference
• /
• 2008.10b
• /
• pp.445-448
• /
• 2008

The key establishment between nodes is one of the most important issues to secure the communication in wireless sensor networks. Some researcher used the probabilistic key sharing scheme with a pre-shared key pool to reduce the number of keys and the key disclosure possibility. However, there is a potential possibility that some nodes do not have a common share in the key pool. The purpose of this paper is to devise a peer to peer key sharing protocol (PPKP) based on Quorum system and Diffie-Hellman key exchange scheme (DHS). The PPKP establishes a session key by creating a shared key using the DHS and then scrambles it based on Quorum system to secure that. The protocol reduces the number of necessary keys than the previous schemes and could solve the non-common key sharing possibility problem in the probabilistic schemes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.7C
• /
• pp.1015-1023
• /
• 2004

In order to protect an exchanged data, it is indispensable to establish a peer-to-peer key between the two communicating nodes. Pre-distributing keys among the nodes is unrealistic in Ad-Hoc network environment because of the dynamic nature of its network topology and the equal authority of its nodes. This paper presents a peer-to-peer key establishment scheme without pre-distributing keys in Ad-Hoc networks. The proposed scheme is based on the Diffie-Hellman key exchange protocol. Main idea is to prevent the falsification of Diffe-Hellman values using some elements of a hash chain. As a result, it is as safe as the underlying hash function against a man-in-the-middle attack. Simulation results have shown that the proposed scheme dramatically reduces the number of messages, and has relatively higher scalability, as compared with the key pre-distribution based scheme.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.15 no.5
• /
• pp.115-124
• /
• 2005

We propose a new binding update(BU) protocol between mobile node(CN) and correspondent node(CN) for the purpose of preventing redirect attacks and DoS attacks observed from the existing BU protocols and enhancing the efficiency of the BU protocol. Home agent plays a role of both authentication server validating BU message and session key distribution center for MN and CN. Also propose the stateless Diffie-Hellman key agreement based on cryptographically generated address (CGA). Suity of our proposed Protocol is analyzed and compared with other protocols. The proposed protocol is more efficient than previous schemes in terms of the number of message flows and computation overhead and is secure against both redirect and DoS attacks.