Secrecy Extraction from Increased Randomness in a Time-Variant MIMO Channel

This paper proposes a practical protocol useful for establishing encryption keys between nodes in a wireless network. The method is designed to enable creation of long keys by extracting the increased randomness inherent in reciprocal time-variant multiple-input multiple-output wireless channels. The presentation provides a strategy for exploiting the degrees of freedom existing in the protocol to decorrelate the information in the public discussion from the key information as well as the channel state information. The paper further discusses several error reduction techniques that can efficiently enhance key agreement between the multiple-antenna nodes. Simulations based on a realistic time-variant channel model demonstrate the efficiency of the key establishment as well as the probability of key agreement for the protocol.