• The Journal of the Korea Contents Association
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• v.17 no.1
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• pp.662-672
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• 2017

Recently, with the development of mobile devices and near field communication, mobile P2P networks have been actively studied to improve the limits of the existing centralized processing system. A peer has limited components such as batteries, memory and storage spaces in mobile P2P networks. The trust of a peer should be discriminated in order to share reliable contents in mobile P2P networks. In this paper, we propose a trust discrimination scheme considering limited resources in mobile P2P environments. The proposed scheme discriminates the trust of a peer by direct rating values using the rating information of the peer and indirect rating values by the other peers. The recent update time is included in the rating information. The proposed scheme reduces the redundant rating information by comparing the recent update times of the rating information. It is shown through performance evaluation that the proposed scheme reduces the number of messages and improves the accuracy of trust over the existing scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.4
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• pp.923-948
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• 2013

The main concern in mobile peer-to-peer (P2P) networks is security because jamming or eavesdropping on a wireless link is much easier than on a wired one and such damage can be incurred without physical access or contact. In particular, authentication has increasingly become a requirement in mobile P2P environments. This paper presents a new mutual authentication mechanism which requires less storage space and maintains a high level of security in mobile P2P networks. The proposed mechanism improves efficiency by avoiding the use of centralized entities and is designed to be agile in terms of both reliability and low-cost implementation. The mechanism suggested in the simulation evaluates the function costs occurring in authentication between the devices under mobile P2P network environment comparing to existing method in terms of basic operation costs, traffic costs, communications costs, storage costs and scalability. The simulation results show that the proposed mechanism provides high authentication with low cryptography processing overhead.

• Journal of Korea Multimedia Society
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• v.17 no.4
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• pp.526-534
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• 2014

Most of the multiplayer games available online are based on a client-server architecture because this architecture gives better administration control to the game providers than peer-to-peer architecture. In this architecture, the server is responsible for all the communication between the connected clients. The weakness of this architecture is its bandwidth requirement and scalability. Peer-to-peer architectures have then been proposed to solve these issues. In this paper, we propose a hybrid client-server architecture in which the game state is partially shared by the mobile terminal to achieve consistency among different players. Like a peer-to-peer architecture, this architecture uses client-side capacities to reduce bandwidth requirements for the server and improves consistency in wireless networks. Client events have different timeliness and consistency requirements according to their nature in the game world. These requirements lead to tasks with different priorities on CPU processing. In the proposed architecture, either the server or the client applies consistency mechanism according to the priority level. Simulation experiments show that the bandwidth of the server in this architecture is smaller than that of the client-server architecture. As a result, the server in the proposed architecture can accommodate more clients with enhancing the scalability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8B
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• pp.521-528
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• 2007

This paper proposes a message authentication scheme to resist potential spam threats in SIP-based VoIP services. Our scheme applies the extended HTTP digest authentication mechanism between the inbound proxy and the UAS to verify that a service request is coming through the valid inbound proxy. The proposed scheme is simple and requires minimal modification the current SIP standards, and effective to filter invalid peer-to-peer spam calls. In this paper, an experimental spam attack using modified open source was tested on a commercial VoIP networks to exploit the possibility of spam attacks in real environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.3
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• pp.954-972
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• 2012

Content Delivery Networks (CDN) server loads that fluctuant necessitate CDN to improve its service scalability especially when the peak load exceeds its service capacity. The peer assisted scheme is widely used in improving CDN scalability. However, CDN operators do not want to lose profit by overusing it, which may lead to the CDN resource utilization reduced. Therefore, improving CDN scalability moderately and guarantying CDN resource utilization maximized is necessary. However, when and how to use the peer-assisted scheme to achieve such improvement remains a great challenge. In this paper, we propose a new method called Dynamic Moderate Peer-assisted Method (DMPM), which uses time series analysis to predict and decide when and how many server loads needs to offload. A novel peer-assisted mechanism based on the prediction designed, which can maximize the profit of the CDN operators without influencing scalability. Extensive evaluations based on an actual CDN load traces have shown the effectiveness of DMPM.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.8
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• pp.586-590
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• 2009

The objective of this paper describes the design of MapReduce over Peer-to-Peer network for dynamic environments applications. MapReduce is a software framework used for Cloud Computing which processing large data sets in a highly-parallel way. Based on the Peer-to-Peer network character which node failures will happen anytime, we focus on using a DHT routing protocol which named Pastry to handle the problem of node failures. Our results are very promising and indicate that the framework could have a wide application in P2P network systems while maintaining good computational efficiency and scalability. We believe that, P2P networks and parallel computing emerge as very hot research and development topics in industry and academia for many years to come.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1015-1024
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• 2011

Mobile P2P protocols in ad-hoc networks have gained large attention recently. Although there has been much research on P2P algorithms for wired networks, existing P2P protocols are not suitable for mobile ad-hoc networks because they do not consider mobility of peers. This study proposes a new cluster-based P2P protocol for ad hoc networks which utilizes peer mobility. In typical cluster-based P2P algorithms, each cluster has a super peer and other peers of the cluster register their file list to the super peer. High mobility peers would cause a lot of file list registration traffic because they hand-off between clusters frequently. In the proposed scheme, while peers with low mobility behave in the same way as the peers of the typical cluster-based P2P schemes, peers with high mobility behave differently. They inform their entrance to the cluster region to the super peer but they do not register their file list to the super peer. When a peer wishes to find a file, it first searches the registered file list of the super peer and if fails, query message is broadcasted. We perform mathematical modeling, analysis and optimization of the proposed scheme regarding P2P traffic and associated routing traffic. Numerical results show that the proposed scheme performs much better than or similar to the typical cluster-based P2P scheme and flooding based Gnutella.

• Journal of KIISE:Information Networking
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• v.31 no.6
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• pp.573-581
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• 2004

Recently, the rapid growth of Internet technology and the deployment of high speed networks make many kinds of multimedia services possible. Preexisting multimedia services are designed based on the client/server model which has the problems such as the network failure and the low speed communication due to the high load on the central server. In order to solve these problems, peer-to-peer networks are introduced and expanded through Internet environments. In this paper, we propose a pure peer-to-peer network based resource discovery mechanism for multimedia services. In the proposed scheme, each host maintains the location information of resources which are recently requested by other hosts as well as that oi the replicas of local resources. The proposed scheme has the faster response time and incurs the smaller traffic than the preexisting discovery schemes in pure peer-to-peer network environments. Also, by decentralizing the location information and differentiating the reply path, our proposed scheme can solve the search result loss problem that occurs when the network is unsettled.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.330-338
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• 2006

Many web cache systems and policies concerning them have been proposed. These studies, however, consider large objects less useful than small objects in terms of performance, and evict them as soon as possible. Even if this approach increases the hit rate, the byte hit rate decreases and the connections occurring over congested links to outside networks waste more bandwidth in obtaining large objects. This paper puts forth a client-cluster approach for improving the web cache system. The client-cluster is composed of the residual resources of clients and utilizes them as exclusive storage for large objects. This proposed system achieves not only a high hit rate but also a high byte hit rate, while reducing outgoing traffic. The distributed hash table (DHT) based peer-to-peer lookup protocol is utilized to manage the client-cluster. With the natural characteristics of this protocol, the proposed system with the client-cluster is self-organizing, fault-tolerant, well-balanced, and scalable. Additionally, the large objects are managed with an index based allocation method, which balances the loads of all clients well. The performance of the cache system is examined via a trace driven simulation and an effective enhancement of the proxy cache performance is demonstrated.

• Journal of Convergence for Information Technology
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• v.10 no.10
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• pp.65-70
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• 2020

With the appearance of Bitcoin that builds peer-to-peer networks for transaction of digital content and issuance of cryptocurrency, lots of blockchain networks have been developed to improve transaction performance. Recently, Joseph Lubin discussed Decentralization Transaction per Second (DTPS) against alleviating the value of biased TPS. However, this Lubin's trust model did not enough consider a security issue in scalability trilemma. Accordingly, we proposed a trust metric based on blockchain size, stale block rate, and average block size, using a sigmoid function and convex optimization. Via numerical analysis, we presented the optimal blockchain size of popular blockchain networks and then compared the proposed trust metric with the Lubin's trust model. Besides, Bitcoin based blockchain networks such as Litecoin were superior to Ethereum for trust satisfaction and data volume.