Design Obfuscation through Selective Post-Fabrication Transistor-Level Programming

摘要

Widespread adoption of the fabless business model and utilization of third-party foundries have increased the exposure of sensitive designs to security threats such as intellectual property (IP) theft and integrated circuit (IC) counterfeiting. As a result, concerted interest in various design obfuscation schemes for deterring reverse engineering and/or unauthorized reproduction and usage of ICs has surfaced. To this end, in this paper we present a novel mechanism for structurally obfuscating sensitive parts of a design through post-fabrication TRAnsistor-level Programming (TRAP). We introduce a transistor-level programmable fabric and we discuss its unique advantages towards design obfuscation, as well as a customized CAD framework for seamlessly integrating this fabric in an ASIC design flow. We theoretically analyze the complexity of attacking TRAP-obfuscated designs through both brute-force and intelligent SAT-based attacks and we present a silicon implementation of a platform for experimenting with TRAP. Effectiveness of the proposed method is evaluated through selective obfuscation of various modules of a modern microprocessor design. Results corroborate that, as compared to an FPGA implementation, TRAP-based obfuscation offers superior resistance against both brute-force and oracle-guided SAT attacks, while incurring an order of magnitude less area, power and delay overhead.