If you were looking for more reasons to loathe LED lights (biological and environmental health risks, high costs) as well as "smart" home devices, and smartphones (cybersecurity vulnerability, health risks from radiation exposure, privacy violations, etc.), researchers have revealed how hackers can exploit power LEDs to additionally spy on you.

From Ars Technica:

Hackers can steal cryptographic keys by video-recording power LEDs 60 feet away

Key-leaking side channels are a fact of life. Now they can be done by video-recording power LEDs.

Dan Goodin

Researchers have devised a novel attack that recovers the secret encryption keys stored in smart cards and smartphones by using cameras in iPhones or commercial surveillance systems to video record power LEDs that show when the card reader or smartphone is turned on.

The attacks enable a new way to exploit two previously disclosed side channels, a class of attack that measures physical effects that leak from a device as it performs a cryptographic operation. By carefully monitoring characteristics such as power consumption, sound, electromagnetic emissions, or the amount of time it takes for an operation to occur, attackers can assemble enough information to recover secret keys that underpin the security and confidentiality of a cryptographic algorithm.