MIO: Enhancing Wireless Communications Security Through Physical Layer Multiple Inter-Symbol Obfuscation

Communications security is a critical and increasingly challenging issue in wireless networks. A well-known approach for achieving information-theoretic secrecy relies on deploying artificial noises to blind the intruders' interception in the physical layer. However, this approach requires a static channel condition for the transmitter and receiver to generate and offset the controllable artificial noise, which can hardly be implemented in real wireless environments. In this paper, we explore the feasibility of symbol obfuscation to defend against the passive eavesdropping attack and fake packet injection attack during the wireless communications. We propose a multiple inter-symbol obfuscation (MIO) scheme, which utilizes a set of artificial noisy symbols (symbols key) to obfuscate the original data symbols in the physical layer. MIO can effectively enhance the wireless communications security. On the one hand, an eavesdropper, without knowing the artificial noisy symbols, cannot correctly decrypt the obfuscated symbols from the eavesdropped packets. On the other hand, a legitimate receiver can easily check the integrity of the symbols key and then reject the fake packets from the received packets. The security analysis reveals that, without considering the initial key, the MIO scheme can achieve information-theoretic secrecy against the passive eavesdropping attack and computational secrecy against the fake packet injection attack. Moreover, we have implemented our approach in a USRP2 testbed and conducted simulations with Simulink tools to validate the effectiveness of MIO in enhancing wireless communications security.