CACI: Dynamic Current Analysis Towards Robust Recycled Chip Identification

Rising incidences of counterfeit chips in the supply chain have posed a serious threat to the semiconductor industry. Recycling of used chips constitutes a major form of counterfeiting attacks. If undetected, they can lead to serious consequences including system performance/reliability issues during field operation and potential revenue/reputation loss for a trusted manufacturer. Existing validation approaches based on path delay analysis suffer from reduced robustness and sensitivity under large process variations. On the other hand, existing design solutions based on aging sensors require additional design/verification efforts and cannot be applied to legacy chips. In this paper, we present a novel recycled chip identification approach, CACI, that exploits differential aging in self-similar modules (e.g., different parts of an adder) to isolate aged chips under large inter- and intra-die process variations. It compares dynamic current (IDDT) signatures between two adjacent similar circuit structures in a chip. We derive an isolation metric based on multiple current comparisons to provide high level of confidence. CACI does not rely on any embedded structures for authentication, thus it comes at virtually zero design overhead and can be applied to chips already in the market. Through extensive simulations, we show that for 15% inter- and 10% intra-die variations in threshold voltage for a 45nm CMOS process, over 97% of recycled chips can be reliably identified.