Hardware Dithering: A Run-Time Method for Trojan Neutralization in Wireless Cryptographic ICs

We introduce a hardware dithering methodology for neutralizing Trojans in integrated circuits (ICs). The proposed approach seeks to make the operating point of an IC an unpredictable moving target during run time. Thereby, the ability of a Trojan to exploit the process variation margins, wherein hardware Trojans typically find breathing room to operate while remaining concealed, is significantly restricted. To demonstrate this hardware dithering concept, we leverage tuning knobs operating on the power and frequency characteristics of the transmission of a wireless cryptographic IC. These knobs are driven by a random number generator, thus forcing the circuit into a random walk in the space of its parametric performances while in normal operating mode. In essence, while the circuit remains within its operating specifications during this random walk, its exact operating point varies, thus muddying the waters for the adversary. Experimental results on the wireless cryptographic IC, which was designed and fabricated in a 0.35μm CMOS technology, corroborate that hardware dithering imposes a significant and unpredictably dispersed bit error rate to the adversary, thereby impeding hardware Trojan operation.