Research On Electromagentic Leakage Emanations Of USB Keyboard

With the wide use of USB keyboards, the TEMPEST problem of USB keyboards is also more and more concerned. As the first input device of computer system, keyboards are often used to transfer some confidential data, such as E-mail and log-in password, etc. However, the keyboard usually produces the electromagnetic wave and release energy, and in the process accompany with useful information leakage. This paper carried out and analysis a series of experiments testing, which research about the electromagnetic leakage emission of USB keyboards. Based on the research of compromising electromagnetic emanations mechanism of information technology devices, we analysis the compromising electromagnetic emanations mechanism of USB keyboards. The structures of USB keyboards contain electronic components leading to the keyboard eventually emit electromagnetic waves to the external. We collected the signals of three different keyboards by using antenna and EMI receiver, confirmed the frequency range. Besides, we carried out the simulation of keyboard cable leakage radiation by CST, compared the simulation results and testing results. Finally, according to the test results and speculative knowledge, we analysis the protect technology of information electromagnetic leakage.