Design Methodology and Validity Verification for a Reactive Countermeasure Against EM Attacks

This paper presents a standard-cell-based semiautomatic design methodology for a new conceptual countermeasure against electromagnetic (EM) analysis and fault-injection attacks. The countermeasure, called the EM attack sensor, utilizes LC oscillators that react to variations in the EM field around a cryptographic LSI caused by a microprobe brought near the LSI. A dual-coil sensor architecture with digital calibration based on lookup table programming can prevent various microprobe-based EM attacks that cannot be thwarted by conventional countermeasures. All components of the sensor core are semiautomatically designed by standard electronic design automation tools with a fully digital standard cell library and hence minimum design cost. This sensor can therefore be scaled together with the cryptographic LSI to be protected. The sensor prototype is designed based on the proposed methodology together with a 128-bit-key composite AES processor in 0.18-μ m CMOS with overheads of only 2 % in area, 9 % in power, and 0.2 % in performance, respectively. The countermeasure has been validated against a variety of EM attack scenarios. In particular, some further experimental results are shown for a detailed discussion.