Computer keyboards are often used to transmit confidential data such as passwords. The sensitive information such as keystrokes could be recovered by using the electromagnetic (EM) waves from the electronic components of the keyboard. In this paper, we have investigated the information leakage on the ground line of the PS/2 serial cable due to crosstalk and radiative coupling. The coupling principles are analyzed firstly. And then, through the experiments we found that the signals of keystrokes could leak to the ground line network which could then be detected on the other power outlets whose share the same electric line. Lastly, the eavesdropping experiments demonstrated that the keystrokes could be reproduced on the other places of the ground line network with no trace.
2. Tosaka, T., Y. Yamanaka, and K. Fukunaga, "Method for determining whether or not information is contained in electromagnetic disturbance radiated from a PC display," IEEE Transactions on Electromagnetic Compatibility, Vol. 53, No. 2, 318-324, 2011.
3. Kuhn, M. G., "Compromising emanations: Eavesdropping risks of computer displays,", Technical Report 577, Computer Laboratory, University of Cambridge, 2003.
4. Van Eck, W., "Electromagnetic radiation from video display units: An eavesdropping risk?," Computers & Security, Vol. 4, No. 4, 269-286, 1985.
5. 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.
6. Du, Y. L., Y. H. Lu, F. Mo, and N. Zhang, "A method for choosing the best frequency range for receiving the electromagnetic compromising emanations from a PC display," Journal of Beijing University of Posts and Telecommunications, Vol. 36, No. 1, 54-58, 2013.
7. Du, Y. L., Y. H. Lu, J. L. Zhang, and Q. Cui, "Estimation of eavesdropping distance from conducted emission on network cable of a PC," 2012 6th Asia-Pacific Conference on Environmental Electromagnetics (CEEM), 347-350, Beijing, China, Nov. 6-9, 2012.
8. Hayashi, Y. I., et al., "Efficient evaluation of EM radiation associated with information leakage from cryptographic devices," IEEE Transactions on Electromagnetic Compatibility, Vol. 55, No. 99, 1-9, 2012.
9. Vuagnoux, M. and S. Pasini, "Compromising electromagnetic emanations of wired and wireless keyboards," The 18th USENIX Security Symposium, 1-16, 2009.
10. Vuagnoux, M. and S. Pasini, "An improved technique to discover compromising electromagnetic emanations," Proc. 2010 IEEE Int. Symp. EMC, Florida, USA, Jul. 2010.
11. Wang, L. T. and B. Yu, "Research on the compromising electromagnetic emanations of PS/2 keyboard," Proceedings of the 2012 International Conference on Communication, Electronics and Automation Engineering, 23-29, Springer, Berlin, Heidelberg, 2013.
12. Backes, M., M. Durmuth, and D. Unruh, "Compromising reflections-or-how to read lcd monitors around the corner," IEEE Symposium on Security and Privacy (2008), 158-169, Oakland, CA, 2008.
13. Asonov, D. and R. Agrawal, "Keyboard acoustic emanations," Proceedings. 2004 IEEE Symposium on Security and Privacy, 3-11, IEEE Computer Society, May 9-12, 2004.
14. Berger, Y., A. Wool, and A. Yeredor, "Dictionary attacks using keyboard acoustic emanations," ACM Conference on Computer and Communications Security (2006), 245-254, New York, USA, 2006.
15. Zhang, L., F. Zhou, and J. D. Tygar, "Keyboard acoustic emanations revisited," ACM Conference on Computer and Communications Security (2005), 373-382, New York, USA, 2005.
16. Paul, C. R., Introduction to Electromagnetic Compatibility, Wiley, New York, 1992.
17. Paul, C. R., "A comparison of the contribution of common-mode and differential-mode currents in radiated emission," IEEE Transactions on Electromagnetic Compatibility, Vol. 31, No. 2, 189-193, 1989.