Physical layer encryption (PLE) has been recently promoted as a new technique to enhance the security for the Internet of things (IoT) sensor transceivers. However, this technique appears with a big challenge that IoT sensor transceivers have limited power and computational resources to execute encryption tasks. Motivated by this issue, in this study, we propose two physical layer encryption methods. We aim to reduce the hardware complexity and preserve the performances of the system. On this basis, they can be applied for IoT sensor transceivers.
The first method is the sign bit encryption method which encrypts only sign bit of the modulated symbols. To evaluate the performances of the system, we simulate in Matlab following the IEEE 802.11ah standard. The simulation results show that our proposed method does not degrade the bit error rate (BER) and packet error rate (PER) performances of the system, while the conventional method degrades the performances about 3 dB. The proposed method uses only XOR-operation; thus, it is low complexity.The second method is a low complexity joint encryption modulation (JEM) method for IoT sensor transceivers. Unlike the sign bit encryption which only encrypts the signed bit, the JEM method encrypts all data. In this method, we merge the mapper and encryption in one block. Our proposed JEM method obtains the following advantages:1) Unlike the conventional method which reduces the BER and PER performances of the physical transceivers up to 3 dB, our proposed JEM method does preserve these performances; 2) The required hardware resources, ASIC area, and power of the proposed JEM method only increase slightly compared to the conventional mapper; 3) The required ASIC area and power of the proposed JEM method are approximately 40 times less than needed for the conventional encryption method.
Further, to prove the feasibility of our method in practice, we design the proposed JEM method and decryption in hardware. We also do the hardware implementation of CORDIC based conventional encryption method to compare with our JEM method.