Adaptive secret key generation in underwater acoustic system

Pre-set secret keys are generally used to encipher and decipher the message in communication systems, including underwater acoustic (UWA) systems. Communication is not secure if the keys are compromised, so we need to generate an adaptive shared secret key. The secret keys are generated adaptively using correlated channel estimation, which reckons on the randomness in the environment and does not require the secrecy of data transferred during the process. This concept is extended in UWA channels with orthogonal frequency-division multiplexing (OFDM) systems and implements a protocol to generate secret keys adaptively based on the channel frequency response (CFR). A secret key generated from the CFR estimation manages the channel coding system, namely a turbo-code. This scheme allows to jointly performing an error control and adaptive coding in only one step. This scheme allows an adaptive security coding without change of the hardware structure of the transceiver devices. In our analysis, BER is used as a measure of the performance of channel estimation and mutual information is used as a measure of secretkey performance.