Performance Enhancement of Multi-User Key Extraction Scheme (MKES) Based on Imperfect Signal Reciprocity

The key extraction scheme using the randomness of the received signal strength is the general technique to secure messages in a wireless environment. However, the imperfect received signal strength reciprocity needs to be overcome to reduce the bit mismatch so it will increase the probability of getting the same key. In this paper, we propose a key extraction scheme between several users, namely a multi-user key extraction scheme that adds a polynomial regression method. This scheme is proven to reduce imperfect signal reciprocity due to noise interference and the limited ability of wireless devices. In addition, we also use the multi-bit extraction method to enhance the speed of key extraction. The results of the tests showed that our proposed multi-user key extraction scheme proved to be able to improve the performance of the key extraction scheme by reducing the bit mismatch up to 30% and improving the key extraction speed up to 35% compared to the existing key extraction scheme.