A Secure Communication Scheme Based on Spatio-Temporal Dynamics of Underwater Acoustic Channel

Underwater acoustic (UWA) communication faces security challenges owing to the open nature of the UWA channel and the uncertainty of the underwater node deployment environment. Key generation schemes based on physical layer information do not require predefined keys or the introduction of additional assistance nodes, which is feasible in resource-constrained underwater scenarios. This article proposes an underwater key generation scheme that includes a channel probing protocol and a key generation algorithm. Based on the spatio-temporal dynamic characteristics of the UWA channel, the amplitude of and time delay information about the channel impulse responses (CIRs) are combined as channel parameters to generate the raw keys. Further, a synchronous probing approach is designed to decrease the probing time difference between the forward and backward channels to enhance the reciprocity of the measurements. The results of the field experiments demonstrated the effectiveness of the key generation scheme and the performance improvements resulting from synchronous probing.