Physical-Layer Cooperative Key Generation With Correlated Wireless Channels

The Internet of Things(IoT)aims to provide ubiquitous connectivity and information gathering capabilities and is an important part of the development of a new generation of communication technologies and network services.However,the presence of a large number of wireless sensor nodes in the Io T makes it difficult to establish key distribution and management mechanisms with traditional cryptography.The key generation technique based on physical layer security,which uses the wireless fading channel resources between legitimate nodes to generate random key information,has the advantage of low complexity and high security,and has good prospects for application in Io T.However,in the existing research on physical layer cooperative key generation,most of the literature does not consider the case of correlation between eavesdropping channels and legitimate channels due to their proximity in practical applications,and there is a lack of research on physical layer key generation techniques for different colluding eavesdropping nodes.This thesis investigates the physical layer cooperative key generation schemes and their performance in the context of wireless multi-relay networks for the Io T,where the eavesdropping channels and the legitimate channels are correlated due to their proximity.The specific research work is summarized as follows:1.A key generation scheme based on traditional channel estimation and its performance are investigated for multi-relay networks with correlated wireless channels,in the case of non-colluding and partially colluding eavesdropping nodes.The basic idea of this scheme is to generate a key which is secret from all the eavesdropping nodes using direct key generation and extraction of the unclassified part of the key,and the key agreement process is mainly consisted by three phases: In phase 1,a number of independent keys are generated by exploiting the difference between the random channels associated with each relay node and the eavesdropping channels;In phase 2,a number of extra independent keys are generated by integrating the residual common randomness associated with each relay pair;In phase 3,the independent keys generated in the first two phases are concatenated into the final key.Further,the achievable key rate performance of this key generation scheme is derived and analysed.The simulation results show that the key rate increases with the number of relay nodes when the eavesdropping nodes are both non-colluding and partially colluding.2.Since the key generation scheme based on traditional channel estimation achieves a low key rate when the eavesdropping nodes are wholly colluding,and the key information is not secret from the relay nodes.Therefore,for multi-relay networks with correlated wireless channels,this thesis also investigates an alternative scheme of key generation based on joint interference and its key rate performance.This scheme changes the training period of traditional channel estimation by making each node send a training sequence simultaneously to jointly interfere with the eavesdropping nodes and the relay nodes,thus generating a key that is secret from all eavesdropping and relay nodes.Further,the achievable key rate performance of this key generation scheme is derived and analysed in the context of the wholly colluding eavesdropping nodes,and the performance of the two key generation schemes is compared by simulations.The simulation results show that the key rate performance of key generation scheme based on joint interference has a significant improvement over the key generation scheme based on traditional channel estimation when the eavesdropping nodes are wholly colluding.