A wireless secret key generation method based on Chinese remainder theorem in FDD systems

The wireless physical channel parameters are recently used to provide secret key. However, the key generation usually suffers from the quantization errors due to the noise, which decreases the key agreement ratio (KAR) between authorized users. Most existing approaches achieve high KAR by discarding some channel parameters which may lower the key generation efficiency and therefore lower the encryption strength. In the frequency-division duplex (FDD) systems, the number of reciprocal parameters, such as the multipath angle and delay, is limited. Therefore how to find a quantization method with high KAR and encryption strength is one of the major problems for secret key generation in FDD systems. In this paper, a robust quantization scheme based on grouping and shifting is proposed, in which all the available parameters are used for key generation. In addition, a key mapping method with error correction based on Chinese remainder theorem (CRT) is proposed to further improve the KAR performance. Simulations demonstrate the effectiveness of the proposed method.