As a new means of eavesdropping, a technique to restore voice from 'bulb vibration' is reported
Negev Ben-Gurion is a system ' Lamphone ' that can eavesdrop on conversation and sound in the room by measuring the vibration of the light bulb from a distant position without installing a camera or a wiretap in the room where the target is Reported by the research team of university security researchers Ben Nassie and others.
Spies Can Eavesdrop by Watching a Light Bulb's Vibrations | WIRED
Lamphone is a system that allows you to listen to the sound of a place several tens of meters away in real time using a laptop PC, telescope, and sensor, and the cost of equipment is about 1000 dollars (about 100,000 yen). The sound can be recovered from the small vibrations generated on the glass surface of the light bulb, 'without hacking the equipment in the room or installing equipment, you can take out all the sound in the room simply by locating the light bulb'. Says Nassie.
In an experiment conducted by Nassi and colleagues, we installed a telescope about 25 meters away from the room in which the light bulb was hung, and installed the photodetector PDA100A2, which is a sensor that detects the vibration of the light bulb, in the eyepiece of the telescope. When you play music or play voice in the room, the sensor acquires the vibration value from the light bulb and outputs the restored voice on the PC in real time. The sensor used this time is also capable of detecting vibrations of a light bulb of several hundred microns.
The image below shows the actual experiment, where a telescope is installed (Eaves dropper) at a corner of a pedestrian bridge 25 meters away from a room with a light bulb (Victim's room).
You can check the sound of 'We will make america great again' reproduced in the room from the vibration of the light bulb from about 3 minutes and 20 seconds in the following movie.
Lamphone: Real-Time Passive Sound Recovery from Light Bulb Vibrations-YouTube
In addition, you can listen to the sound of the Beatles “Let it be” played in the room restored from the following site.
According to a report by Nassi and others, only a suspended light bulb was able to restore the sound, and it has not been verified whether the sound can be restored from the light bulb fixed to the ceiling or the wall. In addition, the loudness of the speaker when playing voice or music in the experiment was the maximum, so it is not clear whether the voice conversation can be detected by the vibration of the light bulb. Nassi's research team used relatively inexpensive equipment in this experiment, so if you use expensive equipment that can detect finer vibrations, it is possible that even a small voice conversation can be restored from the vibration of the light bulb Insists.
Dan Bonneh, a professor of electrical engineering and cryptography at Stanford University, pointed out that Nassie's work could be applied to practical side-channel attacks . “It's the first time we've shown that the vibration of a light bulb can restore sound even if you need a hanging light bulb and a loud sound,” said Bonne. Will be improved to.'
'Lamphone can be used quite practically in espionage,' said Nassi. The reason for publishing the study in the light of its usefulness in espionage was 'not to give spies or law enforcement an advantage, but what technology can be used by both the watcher and the watcher.' 'We don't participate in games that provide tools for eavesdropping. We should know and be aware of all kinds of attacks,' said Nassi. I comment.