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RIS aided Physical Layer Key Generation of IoT network in Static Environments
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  • Jie Yang ,
  • Xinsheng Ji ,
  • Kaizhi Huang ,
  • liang wang ,
  • ge niu ,
  • jianlei zhao
Jie Yang
Information Engineering University, Information Engineering University

Corresponding Author:[email protected]

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Xinsheng Ji
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Kaizhi Huang
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liang wang
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jianlei zhao
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Abstract

Physical layer secret key generation schemes can provide lightweight encryption for resource-constrained Internet of Things (IoT) devices. However, many IoT devices are stationary and the environment is usually static, which leads to ultra-low/zero secret key rates. To circumvent this problem, a novel secret key generation scheme based on Reconfigurable Intelligent Surface (RIS)  is  proposed for Multiple-Input Single-Output  IoT communications. The RIS is introduced into the network, and the phase shifts at RIS are tuned randomly in each frame, which  makes time-varying reflection channels superimposed on the original channels. And then, the secret key capacity of all nodes within the cell coverage area can be remarkably improved. Compared with the existing methods, the scheme is loosely coupled with the existing communication system. The closed-form expressions of secret key capacity taking into account eavesdropping are first derived for the case studies of independent and correlated channels. We can conclude that sharing the same phase shifts randomness will not bring key information leakage. Compared with existing user-introduced randomness schemes, the proposed scheme can  maintain good performance as the number of eavesdropping nodes increases. Further,  the impact of parameters, such as the number of reflecting units, the transmit antennas, and the Rician   factor, on secret key performance are  analyzed respectively, which can offer guidelines for system design. Finally, simulation results verify the theoretical analysis.