Abstract: In this paper, a physical layer security algorithm combined with OFDM modulation is proposed, in order to overcome the disadvantages of the existing physical layer security algorithms which can not resist plaintext cipher-text attack. The modulation process is controlled by a secret key, namely the iterative interpolation of the IFFT input symbols. Theoretical analysis and simulation results have showed that the algorithm not only has a large key space, but also can resist plaintext cipher-text attack. With almost no obviously impact on the original system performance except for a small PAPR increase, the proposed algorithm has great encryption effect and anti-attack ability, which shows a high security.

Key words: plaintext cipher-text attack, physical layer security, iterative interpolation encryption, Orthogonal Frequency Division Multiplexing（OFDM）

摘要： 针对现有的基于OFDM调制的物理层安全算法不能抵抗明文密文对攻击的缺点，提出了一种结合OFDM调制，通过密钥控制调制过程，对IFFT变换前的符号进行迭代插值的物理层安全算法。理论分析和仿真实验表明，算法具有较大的密钥空间，能够抵抗明文密文对攻击。除了峰均比有少量增加外，该算法几乎不改变原系统的性能，具有很好的加密效果和抗攻击能力，表现出较高的安全性。

关键词: 明文密文对攻击, 物理层安全, 迭代插值加密, 正交频分复用