一种利用OFDM系统无线信道相位响应的 密钥提取方案
A Secret Key Extraction Scheme Using Wireless Channel Phase Response of OFDM Systems

针对无线通信系统中利用信道特征提取密钥效率较低的问题,提出了一种利用正交频分复用(OFDM)系统无线信道相位响应的密钥提取方案,该方案首先利用相位随机化的信号对信道相位响应进行探测,并且随机选择一个合法节点通过对探测得到的信道相位进行量化生成初始密钥;其次,将初始密钥进行映射和预均衡处理后发送给对方节点,实现初始密钥的安全分发;最后,合法双方通过信息协商和保密增强获得安全密钥。该方案充分利用了无线信道相位响应的随机性和互易性,只需要一个合法节点来量化产生初始密钥,减少了量化处理,提升了密钥提取性能,同时由于信道相位响应对于收发端之间的距离十分敏感,而保证了该方案的安全性。仿真结果表明,当信噪比为10 dB时,与已有的基于信道相位和信道幅度的密钥提取方案相比,所提方案的密钥容量分别增加34％和70%,密钥不一致率分别降低37％和63％,密钥产生速率分别提高了6.6％和17％,同时所提方案生成的密钥通过了NIST随机性测试。
A secret key extraction scheme based on wireless channel？？phase response of orthogonal frequency？？division multiplexing (OFDM) systems is proposed to solve the low efficiency problem of secret key generation based on the characteristics of wireless channels. The proposed scheme probes the channel？？phase response by using the probe signal with random phase, and a node is randomly selected to generate an initial secret key by quantizing the channel？？phase response. The initial secret key is mapped and pre？？equalized, and then sent to the other node to achieve secure distribution of the initial secret key. Finally, the both sides receive secure secret keys through information consultation and secrecy enhancement. The proposed scheme fully utilizes the randomness and reciprocity of the wireless channel？？phase response and generates the initial secret key by quantifying a single legitimate node. Thus the performance of secret key extraction is improved. Further, the security of the scheme is ensured by the sensitivity of the channel？？phase response to the distance between the transmitter and receiver. Simulation results and comparisons with the existing channel？？phase based scheme and the channel？？amplitude based scheme show that the secret key capacity of the proposed scheme increases by 34％ and 70％, the secret key mismatch rate decreases by 37％ and 63％, and the secret key generation rate increases by 6.6％ and 17％. Moreover, the extracted secret key passes the NIST test