Experts of the company Fox-IT have developed a method of attack on third-party channels, allowing using inexpensive equipment to intercept the AES-256 encryption key from a distance of 1 m. Using available ready-made electronic components for a total cost of $ 224, experts were able to fix the electromagnetic radiation of the attacked computer and in just five minutes to intercept the encryption key. Approaching the equipment at a distance of 30 cm, the researchers managed to reduce this time to 50 seconds.

The equipment used for the attack is a loop antenna attached to an external amplifier and bandpass filters connected to a USB flash drive with radio software. Put together, the device is very compact and can easily hide in your jacket pocket or laptop bag.

The device is able to record radio signals generated by the power consumption of the attacked SmartFusion2 system based on the ARM Cortex-M3 processor. By measuring the leak between the processor and the high-speed bus (AHB), experts were able to link the power consumption level to the encryption process and eventually obtain the key. In the course of the study, specialists determined how the level of power consumption correlates with each byte of information for different encryption processes.

As experts explained, the time of obtaining a key is reduced if you bring the device closer to the computer being attacked.

This is due to the fact that as far as the distance from the system the radio signals become weaker. This technique can be improved with more expensive equipment.

The loop antenna is a directional antenna made in the form of one or several flat turns of wire forming a frame of round, square or rectangular shape.

Bandpass filter - a filter that passes frequencies that are in a certain frequency band. It is a linear system and can be represented as a sequence consisting of a low-pass filter and a high-pass filter.