Evaluation of Information Leakage from Cryptographic Hardware via Common-Mode Current

Yu-ichi HAYASHI  Naofumi HOMMA  Takaaki MIZUKI  Takeshi SUGAWARA  Yoshiki KAYANO  Takafumi AOKI  Shigeki MINEGISHI  Akashi SATOH  Hideaki SONE  Hiroshi INOUE  

IEICE TRANSACTIONS on Electronics   Vol.E95-C    No.6    pp.1089-1097
Publication Date: 2012/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.1089
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electronic Components
information security,  electromagnetic information leakage,  cryptographic modules,  side-channel attacks,  common-mode currents,  

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This paper presents a possibility of Electromagnetic (EM) analysis against cryptographic modules outside their security boundaries. The mechanism behind the information leakage is explained from the view point of Electromagnetic Compatibility: electric fluctuation released from cryptographic modules can conduct to peripheral circuits based on ground bounce, resulting in radiation. We demonstrate the consequence of the mechanism through experiments where the ISO/IEC standard block cipher AES (Advanced Encryption Standard) is implemented on an FPGA board and EM radiations from power and communication cables are measured. Correlation Electromagnetic Analysis (CEMA) is conducted in order to evaluate the information leakage. The experimental results show that secret keys are revealed even though there are various disturbing factors such as voltage regulators and AC/DC converters between the target module and the measurement points. We also discuss information-suppression techniques as electrical-level countermeasures against such CEMAs.