Channel model and sounding method effects on wireless secret key rates

Ensuring data privacy of wireless communication systems has been a challenging problem for various reasons. The simplicity of eavesdropping on wireless transmissions makes the barrier to entry lower for wireless than for wired systems. Due to size and power constraints, wireless systems are sometimes unable to implement the complex cryptographic algorithms that can ensure the privacy of their data, leaving them with weaker schemes that are more easily exploited. However, the wireless security problem has one distinct advantage over the wired problem in that the channel seen by the eavesdropper is not usually correlated with the channel seen by the intended receiver. Recent research in the community has suggested that the randomness inherent in the wireless channel may be exploited to create secret keys dynamically, making simple wireless cryptographic schemes extremely strong and in some applications providing perfect secrecy. In this paper, we present some information theory bounds on key lengths for various wireless channel models and discuss the impact such physical channel-derived dynamic re-keying would have on various applications. We also present some thoughts on proving out the concepts in actual systems.