Exclusion of Forged Files from Multi-source Downloadable P2P Systems

Recently, P2P file sharing systems have been designed to enable peers to concurrently download files fragmented into small blocks from multiple sources to improve the download speed. If block corruption occurs during download, the corresponding block is downloaded again until the corruption does not occur any more. However, malicious peers share corrupt blocks intentionally, called "forged blocks," which cause significant waste of network bandwidth and delay in download completion. In this paper, we propose a method of excluding forged files that comprise forged blocks from the P2P systems. The method has an algorithm for systematically detecting forged files based on corruption reports given by peer agents and preventing the files from being searched by any further queries. Experimental results show that the proposed method sufficiently excludes forged files only, and is tolerable to false reports.