• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.9
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• pp.1947-1954
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• 2009

Service discovery mechanism is a core technique for getting a desired service in MANET(Mobile Ad-Hoc NETwork) environment. However, As feature of MANET, existing mechanisms have some problem that service requester search for trustable service. also it can not support scalability. in this paper, how to reliably support applications such as service discovery on top of MANET. we are firstly finding a trustable service provider and configure DHT(Distributed Hash Table). P2P's DHT can be adopted to service discovery mechanism because P2P and MANET share certain similarities, primarily the fact that both are instances of self-organizing decentralized systems. Especially, Proposed DHT systems used for P2P overlay network can be effective in reducing the communication overhead in service discovery. So proposed mechanism can support for reliably searching required service and scalability. Simulation results show that our mechanism is scalable and outperforms existing service discovery mechanism.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.4
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• pp.695-707
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• 2013

DHT(Distributed Hash Table) networks such as Kademlia are vulnerable to the ID mapping attack caused by the voluntary DHT mapping structure where the location of a node is solely determined by itself on the network topology. This causes security problems such as eclipse, DRDoS and botnet C&C on DHT networks. To prevent ID mapping attacks, we propose a non-voluntary DHT mapping scheme and perform analysis on NAT compatibility, attack resistance, and network dynamicity. Analysis results show that our approach may have an equivalent level of attack resistance comparing with other defense mechanisms and overcome their limitations including NAT compatibility and network dynamicity.

• Journal of KIISE:Information Networking
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• v.34 no.2
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• pp.88-99
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• 2007

P2P systems are distributed data sharing systems, and each node in them plays the role of client as well as server. There are several studies using Distributed Hash Table, such as Chord, CAN, Tapestry, Pastry, but these systems don't consider the physical latency, therefore they have a weakness of difficulty to guarantee stable performance. To improve this problem, we present the TP2P system. This system is a self-organizing hierarchical overlay system and it uses Chord routing mechanism for lookup data. This system is organized by several subnets, each subnet is organized by physically close nodes, and global network organized by all nodes. In each subnet, one node finds a data, it saves in a node in the subnet, therefore it has higher probability to reduce physical lookup latency than Chord system. And each node has global information of some nodes in its subnet, and it is used to lookup data, therefore the number of hops decrease about 25% as well as the physical lookup latecy are reduced.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.217-228
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• 2011

In centralize CDN systems, the content server selection is performed by service node for every user request, and the selected node is notified to the user. In this paper, we present distributed CDN architecture and algorithm in which the request from a user is delivered to the content source by a P2P algorithm utilizing DHT(distributed hash table) through the overlay network and the user selects one of the source nodes based on real-time user-centric criteria. For this purpose, we propose a modified Pastry algorithm for contents registration, search and selection, in addition to the distributed architecture. The proposed architecture has the advantages of load balancing, traffic balancing, scalability, fault-tolerance due to the self-configuration, self-healing attributes of distributed architecture. Various simulation shows the feasibility of the proposed architecture and algorithm, and the performance is compared and discussed for the variations of the proposed scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1294-1310
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• 2010

User authentication using fingerprint information provides convenience as well as strong security. However, serious problems may occur if fingerprint information stored for user authentication is used illegally by a different person since it cannot be changed freely as a password due to a limited number of fingers. Recently, research in fuzzy fingerprint vault system has been carried out actively to safely protect fingerprint information in a fingerprint authentication system. In addition, research to solve the fingerprint alignment problem by applying a geometric hashing technique has also been carried out. In this paper, we propose the hardware architecture for a geometric hashing based fuzzy fingerprint vault system that consists of the software module and hardware module. The hardware module performs the matching for the transformed minutiae in the enrollment hash table and verification hash table. On the other hand, the software module is responsible for hardware feature extraction. We also propose the hardware architecture which parallel processing technique is applied for high speed processing. Based on the experimental results, we confirmed that execution time for the proposed hardware architecture was 0.24 second when number of real minutiae was 36 and number of chaff minutiae was 200, whereas that of the software solution was 1.13 second. For the same condition, execution time of the hardware architecture which parallel processing technique was applied was 0.01 second. Note that the proposed hardware architecture can achieve a speed-up of close to 100 times compared to a software based solution.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5C
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• pp.410-419
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• 2012

This paper proposes a secure and efficient anonymous authentication scheme for health information push service based on indoor location in hospital. The proposed scheme has the following benefits: (1)It is just based on a secure one-way hash function for avoiding complex computations for both health care operations users and health care centers. (2)It does not require sensitive verification table which may cause health care centers to become an attractive target for numerous attacks(e.g., insertion attacks and stolen-verifier attacks), (3)It provides higher security level (e.g., secure mutual authentication and key establishment, confidential communication, user's privacy, simple key management, and session key independence). As result, the proposed scheme is very suitable for various location-based medical information service environments using lightweight-device(e.g., smartphone) because of very low computation overload on the part of both health care operations users and health care centers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.1080-1083
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• 2005

Can speak that DTD is meta data that define meaning of expressed data on XML document. Therefore, in case DTD information is damaged this information to base security of XML document dangerous. Not that attach digital signature on XML document at send-receive process of XML document in this research, proposed method to attach digital signature to DTD. As reading DTD file to end first, do parsing, and store abstracted element or attribute entitys in hash table. Read hash table and achieve message digest if parsing is ended. Compose and create digital signature with individual key after achievement. When sign digital, problem that create entirely other digest cost because do not examine about order that change at message digest process is happened. This solved by method to create DTD's digital signature using DOM that can embody tree structure for standard structure and document.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.89-99
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• 2017

Many works have attempted to solve the scalability, the availability, and the low-latency problems of peer-to-peer (P2P) live video streaming; yet, the problems still remain. While tree-based systems are vulnerable to churn, the mesh-based systems suffer from high delay and overhead. The DHT-aided chunk-driven overlay (DCO) [1] tried to tackle these problems by using the distributed hash table (DHT), which structures into a mesh-based overlay to efficiently share the video segment. However, DCO fully depends on the capacity of the users' device which is small and unstable, i.e., the users' device may leave and join the network anytime, and the video server's bandwidth can be insufficient when the number of users joining the network suddenly increases. Therefore, cloud assist is introduced to overcome those problems. Cloud assist can be used to enhance the availability, the low-latency, and the scalability of the system. In this paper, the DHT is used to maintain the location of the streaming segments in a distributed manner, and the cloud server is used to assist other peers when the bandwidth which required for sharing the video segment is insufficient. The simulation results show that by using the threshold and cloud assist, the availability and the low-latency of the video segments, and the scalability of the network are greatly improved.

• The KIPS Transactions:PartC
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• v.15C no.1
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• pp.19-30
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• 2008

Sensor nodes are used as a storage space in the data centric storage method for sensor networks. Sensor nodes save the data to the node which is computed by hash table and users also access to the node to get the data by using hash table. One of the problems which the data centric storage method has is that queries from many users who are interested in the popular data could be concentrated to one node. In this case, responses for queries could be delayed and the energy of heavy loaded node could be dissipated fast. This would lead to reduction of network life time. In this paper, ALT, Data Centric Storage based on Adaptive Local Trajectory, is proposed as scalable data centric storage method for sensor network. ALT constructs trajectory around the storage node. The scope of trajectory is increased or decreased based on the query frequency. ALT distributes the query processing loads to several nodes so that delay of response is reduced and energy dissipation is also distributed.

• Journal of KIISE
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• v.42 no.8
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• pp.961-971
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• 2015

As a representative area-decomposed algorithm, an area-based quad-trie (AQT) has an issue of search performance. The search procedure must continue to follow the path to its end, due to the possibility of the higher priority-matching rule, even though a matching rule is encountered in a node. A leaf-pushing AQT improves the search performance of the AQT by making a single rule node exist in each search path. This paper proposes a new algorithm to further improve the search performance of the leaf-pushing AQT. The proposed algorithm implements a leaf-pushing AQT using a hash table and an on-chip Bloom filter. In the proposed algorithm, by sequentially querying the Bloom filter, the level of the rule node in the leaf-pushing AQT is identified first. After this procedure, the rule database, which is usually stored in an off-chip memory, is accessed. Simulation results show that packet classification can be performed through a single hash table access using a reasonable sized Bloom filter. The proposed algorithm is compared with existing algorithms in terms of the memory requirement and the search performance.