Listening for Encryption Keys - it works!

Eran Tromer's team again show device vulnerability to to Side Channel Attacks - this time by listening. Computers emit high-pitched noise when working and these sounds leak sensitive information. The team's attack extracted the full 4096-bit RSA decryption keys from laptop computers (of various models), within an hour and experimentally demonstrated such attacks, using a plain mobile phone placed 30cm from the computer, or a more sensitive microphone placed 10 meters away. They even suggest that laser microphones and laser vibrometers will greatly increase the effective range of attacks.

https://link.springer.com/article/10.1007/s00145-015-9224-2