The Research of Using LDPC Encoding and Decoding to Structure Wireless Key Reconciliation Protocol

In the process of key generation based on wireless channel characteristics, in order to reduce the rate of key inconsistent, we usually reconcile key generated by legal both communication sides. The process of key reconciliation commonly take place in the BSC channel, but the negotiation efficiency is low. In order to improve the efficiency of key reconciliation, we propose a protocol mechanism based on LDPC encoding and decoding under a equivalent channel. In this protocol mechanism, the use of Level-Crossing algorithm (LCA) proposed by Mathur12 et al in wireless channel to establish initial key which could be regarded as equivalent channel in this protocol, The mechanism is modelling the negotiated information which are extracted through LCA, inferring the best channel likelihood ratio, and using simple weighted bit-flipping decoding algorithm3-5 to effectively reconcile key. Compared with reconciliation performance under BSC channel, we proposed the performance of protocol is better which can be proved by simulation test. Under the case of SNR>6db, Simulation shows: 1) under the condition of same low threshold, comparing with the key generated by LCA algorithm, using LDPC decoding algorithms further reconcile key under equivalent channel and BSC channel results in that the key inconsistent rate reduce 1 to 2 orders of magnitude. 2) the performance of making use of simple weighted bit-flipping decoding algorithms to reconcile key under equivalent channel is better than performance in the BSC channel, the key inconsistent rate reduce about 1 order of magnitude than the rate under BSC channel.