On-chip current-mode approach to thwart CPA attacks in CMOS nanometer technology

The protection of information that reside in smart devices like IoT nodes is becoming one of the main concern in modern design. The possibility to mount a non-invasive attack with no expensive equipment, such as a Power Analysis Attack (PAA), remarks the needs of countermeasures that aims to thwart attacks exploiting power consumption. In addition to that, designers have to deal with demanding requirements, since those smart devices require stringent area and energy constraints. In this work, a novel analog-level approach to counteract PAA is presented, taking benefits of the current-mode approach. The kernel of this approach is that the information leakage exploited in a PAA is leaked through current absorption of a cryptographic device. Thanks to an on-chip measuring of the current absorbed by the cryptographic logic, it is possible to generate an error signal. Throughout a current-mode feedback mechanism, the data-dependent component of the overall consumption can be compensated, making the energy requirement constant at any cycle and thwarting the possibility to recover sensible information. Two possible implementations of the proposed approach are presented in this work and their effectiveness has been evaluated using a 40nm CMOS design library. The proposed approach is able to increase the Measurements to Disclosure (MTD) of at least three orders of magnitude, comparing to the unprotected implementation. It has to be pointed out that the on-chip current-mode suppressor, based on the proposed approach, is able to provide a very good security performance, while requiring a very small overhead in terms of silicon area (xl.007) and power consumption (xl.07).