Breaking AES256 encryption in 5 minutes

[BoraMurdar]

They only needed to try 8,192 guesses instead of the 2^256 that a brute force would take.​

Security researchers are always on the lookout for breaking encryption algorithms. Brute force techniques aren't viable solutions given the time and resources required, which has led to the development of other, more creative methods of getting around encryption. Using the background electromagnetic radiation given off by a computer system's electronics, a team of researchers at Fox-IT and Riscure were able to recover an AES256 key in just 5 minutes using a $230 device.

This AES attack is a type of side-channel attack and is one of the more popular modern ways to obtain classified or encrypted information. The attacks involve capturing data based on the physical implementation of a system rather than a brute force or exploit of the system itself. Other similar attacks include power analysis to characterize the system doing different encryption operations, acoustic analysis to pick up minute audio queues from the processor, and attacks that purposefully introduce faults into the system.

Image from Techspot​

Full Report
https://www.fox-it.com/en/wp-content/uploads/sites/11/Tempest_attacks_against_AES.pdf