Compromising Electromagnetic Emanations Of Keyboard Input And Infomation Interception

Keyboards are the most commonly used input device in today’s information society. Computers, POS machines, cell phones, printers, ATM all mainly replay on keyboard achieve the purpose of interacting with intelligent systems and information processing equipment. With the popularity of intelligent terminals, information entered through the keyboards involves national security, commercial and trade secrets, private life and so on. TEMPEST attacks for the purpose of information interception pose serious threats to information security of countries, companies and people. In order to implement protection measures via recovering information from compromising electromagnetic emanations of the keyboard, the following tasks were done.First, based on the research of compromising electromagnetic emanations mechanism of information technology devices, the source, signal type, leakage pathways of keyboards’ compromising electromagnetic emanations were systematically analyzed. Focus on conduction coupling and electromagnetic radiation to build corresponding theoretical models to verify the possibility of interception.Second, different methods were applied in a laboratory environment to capture the information of keystrokes. The information we intercepted was carried by electromagnetic emanations via conduction which contain strong signals and radiation which emit a long distance. Meanwhile, according to the characteristics of compromising electromagnetic emanations and PS/2Protocol, we designed an algorithm to recover the information of keystroke. Third, respectively, analyze each module of the interception system which collects the information by conduction and radiation and put forward the idea to realize the miniaturization of interception platform.Fourth, on the basis of traditional TEMPEST protection technology, design the TEMPEST protection of keyboard.