P2p Content Distribution System Of Encoding And Decoding Algorithms In The Design And Realization

Encoding and decoding has become one of the hottest issues in corresponding field, which has attracted the attention both of academic area and industry area. Distributed storage based on content delivery is one important application of P2P (peer-to-peer) network technology. Through analyzing existing content delivery system's technology based on P2P and distributed storage technology of information used in distributed system, combine the advantages of the both, and implement the issuance, management, query, classification download and distributed storage of the information. In the system, if one peer is destroyed, how to protect the confidentiality and integrality of the information has become the common serious problem concerned. This paper aims at study the encoding and decoding arithmetic fitting for P2P content delivery system. To address the design and implementation, the paper compare and analyze present encoding and decoding arithmetic, implementing and testing the arithmetic that fitting for P2P content delivery system. The main work of this paper includes the following aspects.Firstly, design and implement the Vandermonde arithmetic. Vandermonde matrix is the most important part of the Forward Error Correct technique, and multiply the file, creating the normal file data packet and correcting data packet, moreover, the information included in these normal file data packet is the same with that included in the source file data packet. The difficulty of Vandermonde is lies in it's hard to find an appropriate building matrix.Secondly, design and implement the Cauchy arithmetic. Cauchy codes is a kind of Erasure code based on XOR, and is a transmutation of Reed-Solomon Codes, involving in numeric transmutation in Galois field, so the implementation is quite complex. As a kind of Erasure Code, the aim of it is to resist the loss of data packet through adding redundant packet in real time network.Thirdly, study the Tornado arithmetic. Divide the source file into k blocks, then encode and create n blocks, the receiver can recover the source file must receive more than k blocks, but the Tornado arithmetic puts up quite high speed. The paper mainly study these three kind of encoding and decoding arithmetic, based on analysis and comparison, apply the Cauchy Codes into P2P content delivery system, and test the performance through a series of experiments. The test results shows that Cauchy Codes is the most suitable encoding and decoding arithmetic present, and it ensures the integrality of the information.