基于RIS多径随机叠加的物理层密钥生成方案

Key Generation Scheme Based on RIS Multipath Random Superposition

在静态场景下,多径相位和幅度变化缓慢,基于无线信道特征的物理层密钥速率低,难以满足高速数据业务下的通信安全需求。为此,提出了一种基于RIS多径随机叠加的物理层密钥生成方案。首先,收发双方利用RIS天线的实时可控和方向图的捷变特性,通过空间多径的功率谱特性分离多径;然后,在信道相干时间内多次改变空间多径的功率分配,构造等效快变信道,提高密钥源的随机性;最后,通过量化、协商、隐私放大等操作生成一致的安全密钥。仿真结果表明,与现有基于RIS天线的物理层密钥生成方案相比,所提方案一方面通过发掘信道的多径特征提高了信源熵;另一方面通过多径上的功率分配提高了信源的随机性,为密钥速率带来了一定的增益。

In static scenario,the multipath phase and amplitude changes slowly,and the key rate at physical layer based on wireless channel characteristics is low,making it difficult to meet the communication security requirements of high-speed data ser-vices.This paper proposes a key generation scheme based on random superposition of multipaths with the help of RIS.Firstly,both the sender and the receiver use the real-time controllability of the RIS and the agile characteristics of the pattern to separate the multipath in the space through the multipath power spectrum characteristics.Then,the power allocation strategy of multipath is changed many times in the channel coherent time,an equivalent fast-changing channel is constructed,and the randomness of the key source is improved.Finally,a consistent security key is generated through quantization,negotiation,and privacy amplification.Simulation results show that,compared with the existing physical layer key generation schemes based on RIS antenna,the proposed scheme improves the source entropy by exploiting the multipath characteristics of the channel.On the other hand,the randomness of the source is improved by the power distribution on the multipath,which brings a certain gain to the key rate.