Strategy Research On Preventing Pollution Attack On Network Coding In Wireless Network

Comparing with traditional store-and-forward transmission, network coding allows intermediate nodes not only allowed to store-and-forward the incoming packets, but also encode those incoming packets, it helps network coding improving the throughput and reliability of the network by its linear combination property. But in some cases, network coding also brings something we don’t wanted. It is easier for attackers or malicious nodes to use a single packet to corrupt the whole network transmission due to the network coding’s mix mechanism at intermediate nodes. There are some existing mechanisms work against this issue, but some of them are high computational complexity, or need another security channel.This paper’s work are basically focused on make optimizations on both sending scheme and receive scheme of security transmission while being easy to implement. First we introduced a fast grouped tree-liked verifying scheme, achieving lower time cost by using one vector to verify a group of received packets, the number of the packets in a group is decided by the rate of corrupt packets, made the system could adapt to different network conditions. Furthermore, we studied the scalable video coding and combine our scheme with scalable video coding by changing the original tree to an unbalanced tree, increasing the time efficient of lower levels of scalable video coding packets. Second, at verifying side, aiming at reducing time delay of the sending side when original file was too large, we introduce a algorithm based on the average file length, result in reducing time expenses of the sending end. Combining with these two optimizations above, we succeed to improve the system’s time performance, and simulation results show that our scheme have made an advantage of time expense, and helped the network get a better performance.