Modulated symbol-based one-time pad secure transmission scheme using physical layer keys

This paper proposes a novel modulated symbols-based one-time pad (SOTP) secure transmission scheme using physical layer keys. Unlike classical physical layer key generation and exclusive OR (XOR) encryption in the discrete binary space, we design a framework for modulated symbols-based one-time pad (OTP) encryption, where the cryptographic primitive and mathematical model of SOTP is given to build a practical cryptographic protocol. Compared with existing physical layer encryption (PLE) schemes, we provide rigorous proof that the framework can meet perfect secrecy and correctness requirements. In addition, we provide a specific scheme of physical layer OTP secure transmission for quadrature amplitude modulation (QAM) and phase-shift keying (PSK) symbols based on physical layer keys. This scheme realizes the unification of bit encryption and symbol encryption, which can adaptively select the quantization level according to the signal-to-noise ratio (SNR) to minimize the symbol error rate (SER). Further, we analyze the performance quantitatively and derive the closed-form expressions of SER, which indicates that the proposed scheme has a lower SER. Finally, simulation results verify that the proposed symbol-wise OTP secure transmission scheme can achieve perfect secrecy and high reliability.