Secret Key Generation From Route Propagation Delays for Underwater Acoustic Networks

Abstract

With the growing use of underwater acoustic communications and the recent adoption of standards in this field, it is becoming increasingly important to secure messages against eavesdroppers. In this paper, we focus on a physical-layer security solution to generate sequences of random bits (keys) between two devices (Alice and Bob) belonging to an underwater acoustic network (UWAN); the key must remain secret to a passive eavesdropper (Eve) not belonging to the UWAN. Our method is based on measuring the propagation delay of the underwater acoustic channel over multiple hops of the UWAN: this harvests the randomness in the UWAN topology and turns the slow sound propagation in water into an advantage against eavesdropping. Our key generation protocol includes a route discovery handshake, whereby all UWAN devices at intermediate hops accumulate their message processing delays. This enables Alice and Bob to compute the actual propagation delays along each route and to map such information to a sequence of bits. Finally, from these bit sequences, Alice and Bob obtain a secret key. We analyze the performance of the protocol theoretically and assess it via extensive simulations and field experiments.

Anti-Eavesdropping by Exploiting the Space–Time Coupling in UANs

“…As shown in Equations ( 12) and ( 13), given the slot length, adjusting the collector position will change the arrival order of packets sent by sensor nodes. On the contrary, we can also first select an arrival order of packets (e.g., di /v) to satisfy (14) and, then, try to find an achievable location for the collector that satisfies the selected arrival orders. Furthermore, in order to achieve maximal throughput, we want to find a perfect location for the collector under the minimum slot length.…”

“…Unfortunately, the cost and challenge are heavier for implementing encryption and the PLS in UANs than in TRNs. First, a portion of limited bandwidth is taken for regular updates of the secret key, not for data transmission [13,14]. Second, the security rate of the PLS approach is directly related to the estimation accuracy on the dynamic multi-path acoustic channel and underwater noise [15,16].…”

A Lightweight Secure Scheme for Underwater Wireless Acoustic Network

“…The study in [9] proposes to learn the advantage distillation process by using a dataset of observed channels from the legitimate parties and the attacker, respectively. The proposed protocol in [10] extracts common acoustic channel features between receiving and sending nodes. Then, each party uses these features to generate his/her own secret bits via a random sequence generator.…”