It Is Rude to Ask a Sensor Its Age-of-Information: Status Updates Against an Eavesdropping Node

TL;DR

This paper explores how to optimize status update rates in a communication system to balance information freshness at the receiver with security against eavesdroppers, introducing a new metric and analyzing optimal strategies.

Contribution

It proposes a novel metric combining age of information and security, and derives optimal update strategies considering eavesdropper capture probabilities.

Findings

Optimal update rates depend on eavesdropper capture probability.

Counter-intuitive strategies can improve security without sacrificing information freshness.

Extension of age of information framework to include security considerations.

Abstract

We consider periodical status updates between a transmitter and a legitimate receiver, in the presence of an eavesdropper that is sometimes able to capture pieces of information. We assume that, in the absence of such a threat, the connection between the transmitter and the receiver is controlled by the transmitter with the aim to minimize the age of information at the receiver's side. However, if the presence of an eavesdropper is known, the transmitter may further tune the generation rate of status updates to trade off the age of information values acquired by the eavesdropper and the receiver, respectively. To analyze this problem, we first propose a metric that combines both objectives according to a Bergson social welfare framework, and then we solve the problem of finding the optimal generation rate as a function of the probability of data capture by the eavesdropper. This enables us to derive notable and sometimes counter-intuitive conclusions, and possibly establish an extension of the age of information framework to security aspects from a performance evaluation perspective.