Secret key agreement for cooperative wireless communications: bounds and efficient protocol design

We study practical information-theoretically secure secret key agreement protocol design for wireless cooperative communication networks. By assuming the relay selection process is finished in advance, we study the key agreement problem for a classical three-node cooperative wireless communication system over independent additive white Gaussian noise (AWGN) channels. Passive attacks from an eavesdropper collocated with the relay are assumed. We derive upper and lower bounds on the secret key rate under the assumed cooperative wireless system model and find that they are close, which indicates the tightness of the bounds. We then propose an efficient practical secret key agreement protocol with both Bob and the honest relay participating in the public discussion. A compromise between security and efficiency is achieved by the joint advantage distillation and privacy amplification.