Physical layer encryption scheme based on human biometric keys and five-dimensional hyperchaotic systems

Abstract Chaos systems, due to their excellent pseudo randomness, unpredictability, ergodicity, and extreme sensitivity to initial conditions and control parameters, are commonly used in physical layer encryption. However, in practical applications, there are issues such as key leakage or insecurity due to the low dimensionality of chaos systems and the lack of effective association between the key and user identity. To address these issues, this paper proposes a physical layer encryption scheme based on human biometric keys and a five-dimensional hyperchaotic system, achieving multi-level encryption at the physical layer. Firstly, a five-dimensional hyperchaotic system with higher complexity is designed, utilizing biometric parameters as the initial conditions to drive the hyperchaotic system to generate chaotic sequences. Secondly, combining channel block interleaving technology, the chaotic sequences are used to randomly permute the positions of the original data, achieving bit-level randomization and recombination. Thirdly, the constellation diagram of the modulated signal is processed in layers, and the chaotic sequences are used to implement dynamic phase rotation of constellation points. Finally, during OFDM modulation, the chaotic sequences are employed to perturb the carrier index. Simulation results show that the proposed scheme not only provides strong security but also has minimal impact on the performance of the communication system. Compared with traditional chaos-based encryption, the high-dimensional chaos system increases the key space, and the biometric binding mechanism enhances the system’s security.