Privacy, betrayed.(Lamphone Technology)

This post specifically pertains to Lamphone technology.

These days privacy is far different from the dictionary meaning. In recent days, losing privacy primarily remembers hacking/compromising any device which contains important or potential information. Moving onto the next step, researchers develop a new method that can be used by the attackers to listen to our conversations just by staring at a light bulb in the room.

To start with, lamphone is a device developed by the researchers which uses small vibrations of the light bulb caused by the sound waves to retrieve audio produced in the room. Basic innards of regular microphones(as described below) are required to know about lamphone.

There is a three-step process which involves three components in a microphone, a device which converts sound waves into an audio signal, they are

Firstly, a diaphragm- which contains a thin piece of material through which sound waves (air pressure fluctuations) pass and create a mechanical motion to the diaphragm.

Secondly, Transducer- a coil which is attached to the diaphragm moves(caused by the sound waves) in a magnetic field and so by electromagnetic induction a varying current is produced.

Lastly, an analog-to-digital converter(ADC)-which converts electrical signals produced by transducers to digital signals.

There are two methods which an attacker can use:

Internal methods: In this one, all the three components of the microphone, which is compromised by the attacker, described are present in the victim's room.

 

External methods: In this one, only one component(diaphragm- which are objects in the room like a window, bulb etc.) is present in the victim's room, and other two components are present outside.

Now, getting onto lamphone, this uses an external method in which diaphragm is a light bulb.

A telescope which is connected with an electro-optical sensor is used outside the victim's room to measure the vibrations caused by the light bulb in the victim's room. The electro-optical sensor measures the vibration of photons in the collected light and converts them into electrical signals. These electrical signals can be converted to audio by means of any speech converter (Google Cloud speech API)

COUNTER-ACTIONS TO BE TAKEN:

To not let someone steal your privacy some countermeasures have been suggested:

1) weaker bulbs should be used, so that amount of light captured by the telescope will be reduced and henceforth clarity of the sound retrieved is significantly reduced.

2) A heavier bulb must be used so that the vibrations caused to the bulb by the sound waves will be reduced and hence will require more advanced equipment to retrieve the audio.

Attackers use glasses and chips packets to retrieve sound using laser or dynamic microphones.

But that's the idea for another Sci-Hole story.

REFERENCES/CITATIONS:

1)Z. Ba, T. Zheng, X. Zhang, Z. Qin, B. Li, X. Liu, and K. Ren, “Learning-based practical smartphone eaves-dropping with built-in accelerometer.”

2) Photos and concept credit:@misc{cryptoeprint:2020:708,

author = {Ben Nassi and Yaron Pirutin and Adi Shamir and Yuval Elovici and Boris Zadov},title = {Lamphone: Real-Time Passive Sound Recovery from Light Bulb Vibrations},howpublished = {Cryptology ePrint Archive, Report 2020/708},year = {2020},note ={\url{https://eprint.iacr.org/2020/708}}, }

3)S. A. Anand and N. Saxena, “Speechless: Analyzing the threat to speech privacy from smartphone motion sensors,” in 2018 IEEE Symposium on Security and Privacy (SP), vol. 00, pp. 116–133. [Online]. Available:doi.ieeecomputersociety.org/10.1109/SP.2018.00004

4) L. Zhang, P. H. Pathak, M. Wu, Y. Zhao, and P. Mo-hapatra, “Accelword: Energy efficient hotword detec-tion through accelerometer,” in Proceedings of the 13th Annual International Conference on Mobile Systems,Applications, and Services. ACM, 2015, pp. 301–315.

5)R. P. Muscatell, “Laser microphone,” Oct. 25 1983, uS Patent 4,412,105.

6) “Laser microphone,” Oct. 23 1984, uS Patent 4,479,265.

7)A. Davis, M. Rubinstein, N. Wadhwa, G. J. Mysore, F. Durand, and W. T. Freeman, “The visual microphone: passive recovery of sound from video,” 2014.

8)“Pda100a2.” [Online]. Available: https://www.thorlabs.com/thorproduct.cfm partnumber= PDA100A2.