Different applications of covert acoustical mesh networks are presented, including the use for remote keylogging over multiple hops. It is shown that the concept of a covert acoustical mesh network renders many conventional security concepts useless, as acoustical communications are usually not considered. Finally, countermeasures against covert acoustical mesh networks are discussed, including the use of lowpass filtering in computing systems and a host-based intrusion detection system for analyzing audio input and output in order to detect any irregularities.
Tag Archives: acoustical networks
Ultrasonics for Local Area Communication
I intend to examine the prospects of ultrasonics for wireless, local area communication. In other words, I will try to decide whether or not it might be feasable to create a system for objects in the same room to communicate with one another by sharing information through ultrasonic sound. To do this, I will work through issues such as the spectrum, transducers, beam width, transmission distance, bandwidth, and noise.
This work builds on the work done by Vadim Gerasimov, in the Things That Talk project, that transmits data by sound in the audible range. His site is a good starting point to visit before working through this information.
Acoustic Vector Sensors
In acoustics this movement of air is called particle velocity. The Microflown sensor is based upon MEMS technology, and uses the temperature difference in the corss section of two extremely sensitivy platinum wires that are heated up to 200°C in order to determine Acoustic Particle Velocity. When air flows across the wires, the first wire cools down a little and due to heat transfer the air picks up some heat. Hence, the second wire is cooled down with the heated air and cools down less than the first wire. A temperature difference occurs in the wires, which alters their electrical resistance. This generates a voltage difference that is proportional to the Particle velocity and the effect is directional: when the direction of the airflow reverses, the temperature difference will reverse too.