Study on Information Leakage of Input Key due to Frequency Fluctuation of RC Oscillator in Keyboard

Masahiro KINUGAWA  Yu-ichi HAYASHI  Takaaki MIZUKI  Hideaki SONE  

IEICE TRANSACTIONS on Communications   Vol.E96-B    No.10    pp.2633-2638
Publication Date: 2013/10/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E96.B.2633
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electromagnetic Compatibility(EMC)
EM information leakage,  integrated oscillator,  information security,  RC oscillator,  

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Recently, it has been shown that electromagnetic radiation from electrical devices leaks internal information. Some investigations have shown that information leaks through the clock frequency and higher harmonic waves. Thus, previous studies have focused on the information leakage from information processing circuits. However, there has been little discussion about information leaks from peripheral circuits. In this paper, we focus on the oscillation frequency of the integrated RC oscillators. In this paper, we use a keyboard as a device that includes a RC oscillator. Then experiments observed information leaks caused by key inputs. Our experiments show that frequency fluctuations cause information leakages and clarify what information can be acquired from the fluctuation. Then, we investigate the possibility of information leaking from peripheral circuits through modulated signals which are radiated by the peripheral circuits.