The use of wireless channel reciprocity properties for secret key generation has been an attractive method for many wireless applications. Most of the available methods rely on some sort of pilot signalling from the transceiver. This reduces the intrinsic security of the generated key. In this paper we have introduced a novel key generation and exchange method that requires no pilot signalling and have also included an algorithm to restore wireless channel reciprocity properties for varying transmission power. Finally we presented information theoretic analysis and the result of our implementation on off-the-shelf TelosB motes.