The Research On Wireless Network Coding Overhearing And Security

Wireless network coding can greatly improve network throughput,decrease end-toend delay and reduce data transmission times.Due to the open medium characteristics,combined with network coding,wireless overhearing further improve the efficiency and network performance of network coding.Therefore,wireless network coding overhearing gradually becomes a research hotspot at home and abroad.Meanwhile,the open medium property offers a lot of opportunity to challenge wireless network coding,such as eavesdropping attacks and polluting attacks.These two kinds of attacks become urgent issues for wireless network coding.Therefore,in this dissertation,we make deep research on both wireless network coding overhearing and security.The main contributions and creative are described as the following:(1)Wireless network coding overhearing.The combination of wireless overhearing and network coding greatly further improve network performance.In wireless overhearing,when overhearing buffer size is constrained,overhearing strategy directly determines the performance of network coding.Focusing on this issue,we put forward a data packet switching and scheduling(DPSS)strategy.First,when overhearing buffer is full,meanwhile,the sink codes have listened new packets,codes will drop the new packets but record the IDs of the dropped packets;Second,intermediate codes get the packets' information of overhearing buffer,then switch the packets of coding queue according to the packets information of overhearing cache.Finally,sink nodes delete the packets which have been used for decoding,and add the newly-coming packets in the cache.Experimental results demonstrate that,our scheme further improve the network performance gains of network coding.(2)Group-xoring network coding.An outstanding property of network coding is that it can significantly decrease the data transmission times,while in classical linear network coding,such as xor coding,although this coding scheme is very simple and low overhead,it introduce repeated transmission of data,especially in wireless overhearing.How to research a simple and efficient coding scheme becomes a job of this research.Coding node gets the fundamental packet set according to the packet's number relation among different flows.Then,makes modulo and division operation among packets' amount from different flows in coding queue,and gets the coding rounds and the remainder packets quantity,according to which,coding node performs group XOR-ing operation on packets in coding queue.Meanwhile,the sink nodes choose the corresponding overheard original packets to decode received packets step-by-step,and finally obtain the corresponding data packet sent by the source node.Experimental results demonstrate that our scheme can further improve the network performance.(3)Secure anti-eavesdropping attacks network coding.The existing anti-eavesdropping attacks can mainly be categorized into two kinds,homomorphic hash and homomorphic signature.These two schemes are both based on homomorphic encryption,they utilize the complexity and high security of homomorphic encryption to resist eavesdropping attacks.However,these two schemes incur large computational overhead to coding nodes,resulting in huge end-to-end delay and high energy consumption.To address this issue,we propose an anti-eavesdropping coding scheme which is of low overhead and high security.Source node linearly combines the packets,encrypts the coding coefficient with the next-hop node's identify label and signs the encrypted data with its private key;Intermediate node verifies the signature and decrypts the encrypted coefficient,recodes the received packets with linear network coding and encrypts the recoding coefficient as well as signature;Sink node decrypts the coefficient data after verifying it,meanwhile,puts the coefficient into the matrix,finally,sink nodes yield their intended data by Gaussian elimination method.Numerous results demonstrate that,compared with homomorphic scheme,our scheme can significantly improve the network performance,such as low delay and high throughput and et al.(4)Secure anti-pollution attacks network coding.Pollution attacks is based on eavesdropping attacks.The existing schemes on pollution attacks are mainly divided into two categories,data verification and error correction.Data verification is based on public key encryption system,such as homomorphic hash and homomorphic signature,but this kind of scheme introduces extra complicated computation overhead.As a result,it inevitably incurs high computational delay.While the latter scheme,namely,error correction,aims at correcting each data block to protect the received data from being polluted.However,this kind of scheme is limited to very small number of pollution packets.To address these problems,we put forward a high performance and low overhead scheme which can well resist pollution attacks.Our scheme utilizes key pre-distribution and message authority code.Based on multi-cast property,legitimate nodes use next-hop nodes' public key to generate multiple MACs.Each MAC is attached to the source data.Therefore,every node can use its secret key to make verification on received data,and filter the polluted data at a high probability.In summary,this dissertation first researches the wireless overhearing's improvement on wireless network coding gains,and propose a DPSS strategy to resolve the drawbacks of wireless overhearing;then,according to the shortcomings of xor coding in wireless overhearing,we put forward a group-xoring coding scheme;finally,to address the security issues in wireless network,we present anti-eavesdropping and anti-polluting attacks schemes.These two schemes guarantee the security of wireless network coding at great extent.