NRIT: Non-Redundant Indirect Trust Search
Algorithm for a Cross-Domain based CDNi-P2PArchitecture
Shi Li, Inshil Doh, Kijoon Chae
Department of Computer Science and Engineering, Ewha Womans University, Seoul, Korea
lishi1116@ewhain.net, isdoh1@ewha.ac.kr, kjchae@ewha.ac.kr

Abstract—A content delivery network (CDN), as a distributed network architecture, enhances efficient delivery of content. Theinterconnection of different CDNs (CDNi) further improves efficiency and the experience of end users. As another distributed
network with high availability and high performance, a peer-to-peer (P2P) network can provide efficient resource sharing. Tocombine the advantages of the two networks, we propose a hybrid CDNi-P2P architecture, along with trust management models toachieve more efficient content delivery. In CDNi-P2P architecture, end users can obtain the requested content from the nearest CDNedge server, and can also share these contents with other users in the same domain as a P2P network. After the transactions, users
can rate each other based on the reputation evaluation method adopted in the system. For some mobile users, they can move among
different domains and share the contents who have with the end users in different system. In general, different systems adopt
different reputation evaluation standards. This leads to disparate trust values for mobile users in different systems. Based on thearchitecture, we propose two trust models to solve this problem: a local trust model and a cross-domain trust model. To evaluate
reputation more effectively and accurately, we also propose a search algorithm for the trust model called the non-redundant indirecttrust search algorithm (NRIT-SA). Using the proposed trust models, a mobile user can transform his/her local trust into mobile trust
in a new domain. We thus avoid disparate trust values for a single user in different domains and improve the availability of thecontent possessed by mobile users as they move among different domains. The result of the performance analysis shows that when
there is a high connectivity degree of users in the system, the calculation time of the proposed NRIT-SA tends to be stable. And
depending on the comparison result with the full search algorithm, NRIT-SA shows more efficient calculation performance and morereliable result.
Keyword—CDNi, Cross Domain, Mobile, Reputation Evaluation, Trust
Shi Li received the B.S. degree in the Department of computer science and engineering from Harbin Institute of Technology, China in2010. She is currently a Ph.D. candidate in the Department of computer science and engineering at Ewha Womans University, Seoul,Korea. Her research interests include sensor network security, smart grid security and content delivery network security.

Inshil Doh received the B.S. and M.S. degrees in Computer Science at Ewha Womans University, Korea, in 1993 and 1995,
respectively, and received the Ph.D. degree in Computer Science and Engineering from Ewha Womans University in 2007. From1995-1998, she worked in Samsung SDS of Korea to develop a marketing system. She was a research professor of Ewha Womans
University in 2009~2010 and of Sungkyunkwan University in 2011. She is currently an assistant professor of Computer Science andEngineering at Ewha Womans University, Seoul. Her research interests include wireless network, sensor network security, and M2M
network security.

Kijoon Chae received the B.S. degree in mathematics from Yonsei University in 1982, an M.S. degree in computer science fromSyracuse University in 1984, and a Ph.D. degree in electrical and computer engineering from North Carolina State University in 1990.
He is currently a professor in Department of Computer Science and Engineering at Ewha Womans University, Seoul, Korea. His
research interests are network security including sensor network, smart grid, CDN, SDN and IoT, and network protocol design andperformance evaluation. He is the corresponding author of this paper.