Video-Based Cryptanalysis: Extracting Cryptographic Keys from Video Footage of a Device’s Power LED

Ben Nassi, Etay Iluz, Ofek Vayner, Or Cohen, Dudi Nassi, Boris Zadov, and Yuval Elovici: We were able to recover secret keys from non-compromised devices using video footage of their power LED obtained by commercial video cameras. In this paper, we present video-based cryptanalysis, a new method used to recover secret keys from a device by analyzing video footage of a device’s power LED. We show that cryptographic computations performed by the CPU change the power consumption of the device which affects the brightness of the device’s power LED. This is done by obtaining video footage of a device’s power LED (in which the frame is filled with the power LED) and exploiting the video camera’s rolling shutter to increase the sampling rate by three orders of magnitude from the FPS rate (60 measurements per second) to the rolling shutter speed (60K measurements per second in the iPhone 13 Pro Max). Via Sam Bent. They recovered a 256-bit ECDSA key from a smart card reader 16 meters away,…