Information leakage of general input operations using button images in graphical user interface on touch screen monitors was experimentally investigated from images reconstructed by receiving the electromagnetic noise. In the experimental investigations for input operations of a personal identification number, it was confirmed that when a button image was touched, the touched button image can be identified from the reconstructed button images. This kind of information leakage has originated the fact that the touched button image has changed the color for informing the operator which button image was touched. From the elucidation of the image reconstruction mechanism, it was found that the information leakage has been caused by the magnitude of the emitted signal that results from the analog voltage differences of the RGB signals between neighboring pixels on the monitor. Therefore, a countermeasure method was proposed from the viewpoint of the combination of the colors of the button images and of the background or of the numerals in the button images. The countermeasure method was then applied to the previous input operations of a personal identification number. From the experimental results for the countermeasure method, it was confirmed that the touched button image cannot be identified from the reconstructed button image. As a result, the proposal countermeasure method can prevent effectively the information leakage of input operations on touch screen monitors due to the electromagnetic noise.
2. X.1051, "Information Security Management System | Requirements for Telecommunications (ISMS-T)," International Telecommunication Union | Telecommunication Standardization Sector (ITU-T) , 2004.
3. RFC2828, "\Internet security glossary," Internet Engineering Task Force, 2000.
4. CISPR 22, "Information technology equipment | Radio disturbance characteristics | Limits and methods of measurement," International Electrotechnical Commission (IEC), 2008.
5. IEC 61000-6-3, "Electromagnetic Compatibility (EMC) --- Part 6-3: Generic Standards --- Emission Standard for Residential," Commercial and Light-Industrial Environments International Electrotechnical Commission (IEC), 2006.
6. K.48, "EMC requirements for telecommunication equipment Product family Recommendation ," International Telecommunication Union | Telecommunication Standardization Sector (ITUT), 2006.
7. MIL-STD-461F, "Requirements for the control of electromagnetic interference characteristics of subsystems and equipment," Department of Defense Interface Standard (United State of America), 2007.
8. Van Eck, , W., "Electromagnetic radiation from video display units: An eavesdropping risk?," Computers and Security, Vol. 4, No. 4, 269-286, 1985.
9. Kuhn, , M. G., "Compromising emanations: Eavesdropping risks of computer displays," Tech. Rep. UCAM-CL-TR-577, 2003.
10. Vuagnoux, , M. and S. Pasini, "An improved technique to discover compromising electromagnetic emanations," Proc. 2010 IEEE Int. Symp. EMC, 2010.
11. Sekiguchi, , H. and S. Seto, "Estimation of receivable distance for radiated disturbance containing information signal from information technology equipment ," Proc. 2011 IEEE Int. Symp. EMC, 2011.
12. Sekiguchi, H., "Measurement of radiated computer RGB signals," Progress In Electromagnetics Research C, Vol. 7, 1-12, 2009.
13. Sekiguchi, , H. and S. Seto, "Measurement of computer RGB signals in conducted emission on power leads," Progress In Electromagnetics Research C, Vol. 7, 51-64, 2009.
14. Kuhn, , M. G., "Filtered-tempest fonts,".
15. Beyond IT Co., Ltd., CrypType,.
16. Suzuki, , Y. and Y. Akiyama, "Jamming technique to prevent information leakage caused by unintentional emissions of PC video signals ," Proc. 2010 IEEE Int. Symp. EMC, 2010.
17. Watanabe, T., H. Nagayoshi, T. Urano, T. Uemura, and H. Sako, "Countermeasure for electromagnetic screen image leakage based on color mixing in human brain ," Proc. 2010 IEEE Int. Symp. EMC, 2010.
18. Sekiguchi, , H., "Information leakage of input operation on touch screen monitors caused by electromagnetic noise," Proc. 2010 IEEE Int. Symp. EMC, 2010.
19. Sekiguchi, , H., "Software countermeasure technique against information leakage threat of button input operations in display image caused by radiated electromagnetic noise from information equipments ," IEICE Trans., Vol. J92-B, No. 7, 1113-1120, 2009.
20., "Monitor Timing Specifications, Version 1.0, Revision 0.8,", 1998.