Efficient key generation leveraging wireless channel reciprocity for MANETs

Wireless channel reciprocity ensures that transceivers can generate the shared secret key from their communicating channels. However, various interferences in real environments make channel measurement sequences of different transceivers are highly correlated accompanying with many discrepancies. Then, if these measurements are directly quantified (and encoded) to bit sequences, the bit mismatch rate might be extremely high. Consequently, the efficiency and security of key generation might be reduced since some information might be leaked during key agreement. In this paper, an efficient key generation scheme is proposed, which is available to generate the shared secret key for transceivers even facing the referred challenge. During key generation, curve fitting is implemented to pre-process measurements so that the reciprocity of outputs of curve fitting processes are better than original channel measurements. Then, the bit mismatch rate can be greatly reduced when these outputs are used to generate bit sequences. To extract the shared bit sequence, the interactive Cascade is implemented during information reconciliation. Finally, 2-universal hash functions are used to achieve privacy amplification so that the leaked information can be eliminated and randomness of the shared key can be guaranteed. Several experiments in real mobile scenarios are conducted to evaluate the proposed scheme, where the received signal strength measurements are derived from heterogeneous devices. The results show that the implementation of pre-processing can effectively reduce the bit mismatch rate and the proposed scheme can efficiently generate shared secret keys for transceivers in real environments.