Reconstruction of leaked signal from USB keyboards

Key information of universal serial bus (USB) keyboards at keystroke can be found by analyzing the electromagnetic emanations from the USB cable. The problem with information security such as eavesdropping arises from these emanations. This paper presents the emission phenomenon according to the signal transmission mechanism of USB keyboards and method of measurement and analysis of the leaked signal. Electromagnetic emanations were measured by the antenna and receiver and analyzed by the several signal processing algorithms.