Tuesday, May 24, 2022

New countermeasure against unwanted wireless surveillance

The intelligent reflective surface IRShield is positioned next to a Wi-Fi router to disguise the environment-dependent radio channel.
Credit: CASA, Michael Schwettmann

Wirelessly functioning devices are now omnipresent. However, wireless communication endangers privacy: passive eavesdroppers can access sensitive data through intercepted high-frequency signals.

Smart devices should make our everyday life easier. At the same time, however, they are a gateway for passive eavesdropping. In order to prevent possible monitoring of the movement profile in your own four walls, researchers from the Max Planck Institute for Security and Privacy, the Horst Görtz Institute for IT Security at the Ruhr University Bochum and the Technical University of Cologne have a new system developed to protect privacy in wireless communication. The researchers will present the process, based on the technology of intelligent reflective surfaces, on 24. May 2022 at the IEEE Symposium on Security and Privacy.

Monitoring of premises remotely

Almost all Internet of Things devices - such as voice assistants, locks and cameras - rely on wireless connections based on high-frequency radio signals. Although cryptographic methods are already used to ensure the confidentiality of data, passive eavesdroppers can still use sensitive information from intercepted high-frequency signals. This is possible because the propagation of the signals is influenced by the physical environment of the devices - by reflections on walls, objects and people present. Attackers can perceive such effects remotely and, by using simple statistical methods, conclude, for example, that a person is moving in the monitored room.

Innovative approach to wireless eavesdropping

In order to counteract this method, which is called "adversarial wireless sensing", the team examined the use of intelligent reflective surfaces, or IRS for short for intelligent reflecting surfaces. The IRS are considered to be future-oriented technology for setting up intelligent radio environments: Many reflective elements are distributed over a surface, and their reflection behavior can be individually and electronically adjusted. This enables the elements to dynamically manipulate the radio waves that hit them. For example, IRS can be configured to reflect signals in a certain direction.

With their approach, researchers worldwide are the first to propose IRS as a practical countermeasure against passive wireless eavesdropping attacks. As a new countermeasure, they have developed a system called "IRShield": IRShield uses a specially developed algorithm that creates a random IRS configuration, i.e. aligns the reflective elements randomly. This veils the wireless channels so that attackers can no longer read information about movements in space from the signal.

IRShield is designed as an independent, data protection-friendly extension for plug-and-play integration into existing wireless infrastructures. In contrast to previous research in the field, the researchers with IRShield were able to meet three important requirements with their approach: the solution works independently of the devices used, the radio waveforms and standards used, it does not impair the quality of the wireless connection and it achieves a very high one Channel veiling.

Forward-looking research results

The team tested how successfully IRShield can prevent state-of-the-art attacks to detect human movements with commercially available Wi-Fi devices: 95 percent of the attacks were unsuccessful thanks to IRShield. In certain cases, motion detection was largely impossible regardless of the attacker's strategy. The team's results can serve as a starting point for many other works, such as optimizing IRS configurations or examining methods of more advanced attackers.

Source/Credit: Ruhr University Bochum

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