Tel Aviv University and Technion security researchers have discovered a new method to steal sensitive data from a target air-gapped computer. The team is the same group of researchers who had experimented a number of different methods to extract data from computers using just a radio receiver and a piece of pita bread. The researchers successfully extracted the secret key after observing around 66 decryption processes, each lasting about 0.05 seconds, resulting in a total measurement time* of about 3.3 secs.3 seconds.
Source: https://thehackernews.com/2016/02/hacking-air-gapped-computer.html