基于哈希方法的物理层认证机制

Physical Layer Authentication Scheme Based on Hash Method

现有物理层挑战-响应认证机制使用无线信道信息掩藏密钥生成认证响应,一旦攻击方获得合法信道信息,则可直接破解密钥。针对上述问题,该文借鉴曲线匹配原理,提出一种基于哈希方法的物理层认证机制。首先,认证双方提取无线信道特征,并和认证密钥组合得到初始认证向量,该向量被等效为一条曲线;随后,采用具有容错性的单向哈希函数将该曲线映射为低维的哈希矢量,用作认证响应;最后,认证方根据需求设置认证门限,并根据响应的匹配结果进行判决。性能分析表明,所采用的哈希方法实质为欠定方程组,攻击方无法根据低维哈希矢量还原曲线信息,从而无法破解密钥;仿真结果表明,在攻击方窃取了合法信道信息的条件下,在4 d B时,现有挑战-响应机制攻击率约为0.5,该文所提机制可实现攻击率小于510-。

To solve the problem of key leakages in existing physical layer challenge-response authentication schemes a physical layer authentication scheme based on hash method is proposed. The channel characteristics are extracted and linked with the key which can be regarded as a curve. Then a fault-tolerant hash function is employed to map the curve into a response with lower dimension. The authenticator lastly sets the threshold according to the authentication requirement and further to verify the identity of the requester. The hash function is an underdetermined system and attackers can not recover the curve according to the response. Simulation results prove the effectiveness of the scheme whose attack rate is less than 10-5 while attack rates for existing schemes are almost 0.5 under the SNR of 4 dB.