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System-on-chip (SoC) developers increasingly rely on pre-verified hardware intellectual property (IP) blocks often acquired from untrusted third-party vendors. These IPs might contain hidden malicious functionalities or hardware Trojans that may compromise the security of the fabricated SoCs. Lack of golden or reference models and vast possible Trojan attack space form some of the major barriers in detecting hardware Trojans in these third-party IP (3PIP) blocks. Recently, supervised machine learning (ML) techniques have shown promising capability in identifying nets of potential Trojans in 3PIPs without the need of golden models. However, they bring several major challenges. First, they do not guide us to an optimal choice of features that reliably covers diverse classes of Trojans. Second, they require multiple Trojan-free/trusted designs to insert known Trojans and generate a trained model. Even if a set of trusted designs are available for training, the suspect IP can have inherently very different structure from the set of trusted designs, which may negatively impact the verification outcome. Third, these techniques only identify a set of suspect Trojan nets that require manual intervention to understand the potential threat. In this paper, we present VIPR, a systematic machine learning (ML) based trust verification solution for 3PIPs that eliminates the need for trusted designs for training. We present a comprehensive framework, associated algorithms, and a tool flow for obtaining an optimal set of features, training a targeted machine learning model, detecting suspect nets, and identifying Trojan circuitry from the suspect nets. We evaluate the framework on several Trust-Hub Trojan benchmarks and provide a comparative analysis of detection performance across different trained models, selection of features, and post-processing techniques. We demonstrate promising Trojan detection accuracy for VIPR with up to 92.85% reduction in false positives by the proposed post-processing algorithm.

Field Programmable Gate Arrays (FPGAs) provide a flexible compute platform for quick prototyping or hardware acceleration in diverse application domains. However, similar to the global semiconductor life-cycle in the modern supply chain, FPGA-based product development includes processes and interactions with potentially untrusted parties outside the traditional scrutiny of a completely in-house development cycle. An untrusted party or software can maliciously alter a hardware intellectual property (IP) block mapped to an FPGA device during various stages of the FPGA life-cycle. Such malicious alterations, also known as hardware Trojan attacks, have garnered significant research into their detection and prevention in the context of application-specific integrated circuit (ASIC) design flow. However, Trojan attacks in FPGAs have not enjoyed this same attention. Designers often rely on mapping ASIC-specific solutions and evaluation benchmarks to the FPGA domain, which leaves much of the FPGA-specific Trojan space uncovered. We note that the distinctive business model as well as the architectural configurations of FPGAs present unique opportunities for Trojan attacks to an adversary. To this end, we introduce a framework to automatically explore the hardware Trojan attack space in FPGA netlists. It is capable of inserting different types of FPGA-specific Trojans in a netlist enabling rapid exploration of potential Trojan attacks in an FPGA design: soft-template, monolithic, and distributed dark silicon. Soft template Trojans use behavioral templates with random synthesis constraints to increase Trojan structural diversity. Monolithic and distributed dark silicon Trojans use the under-utilized input space (FPGA dark silicon) in FPGA primitives to realize Trojans with effectively zero area and power footprint. Further optimizations are also presented to remove any potential delay impact. We evaluate our framework by generating over 1300 Trojan-inserted benchmarks using each of the introduced FPGA Trojan classes and comparing the impact on utilization, delay, and power.