The offshore outsourcing introduces serious threats to semiconductor suppliers and integrated circuit(IC) users for the possibility of hardware trojans (HTs). To alleviate this threat, IC designers use the active defenses against HTs which are implanted by the malicious manufacturer. In this paper, a game-theoretic framework based on fuzzy theory is proposed to obtain the optimal strategy. It analyzes the interactions between the active defense designer and the malicious manufacturer. The attack and defense on IC is formulated as a noncooperative dynamic game. The active defense strategy is decided in IC design. And the overall payoff including design costs and losses avoided is optimized. Subsequently, the HT is implanted considering the implantation cost as well as the damage caused by it. To solve the problem of uncertain payoff caused by insufficient information, fuzzy variable is used to represent the influence of the defense coverage rate on the payoff. In order to verify the applicability of fuzzy variable in dynamic game framework, the existence of pure strategy Nash equilibrium in the game is proved. A solution algorithm for pure strategy Nash Equilibrium is proposed to obtain the optimal strategy of attacker and defender. Thanks to the case study of Field Programmable Gate Array (FPGA), the proposed framework is feasible for HT attack and defense game.

The globalization of integrated circuit (IC) design and fabrication has given rise to severe concerns with respect to modeling strategic interaction between malicious attackers and Hardware Trojan (HT) defenders using game theory. The quantitative assessment of attacker actions has made the game very challenging. In this paper, a novel rough set theory framework is proposed to analyze HT threat. The problem is formulated as an attribute weight calculation and element assessment in an information system without decision attributes. The proposed method introduces information content in the rough set that allows calculation of the weight of both core attributes and non-core attributes. For quantitative assessment, the HT threat is characterized by the closeness coefficient. In order to allow HT defenders to use fast and effective countermeasures, a threat classification method based on the k-means algorithm is proposed, and the Best Workspace Prediction (BWP) index is used to determine the number of clusters. Statistical tests were performed on the benchmark circuits in Trust-hub in order to demonstrate the effectiveness of the proposed technique for assessing HT threat. Compared with k-means, equidistant division-based k-means, and k-means++, our method shows a significant improvement in both cluster accuracy and running time.

High-frequency GaN Schottky barrier diodes (SBDs) demonstrate considerable potential for enhancing device power density in astrophysics and atmospheric remote sensing applications. However, the insufficient investigation of space irradiation effects critically limits the implementation of high-frequency GaN SBDs in space-borne systems. This work investigates the impact of 1.335 GeV Ta ion irradiation on the electrical performance and defect characteristics of high-frequency GaN SBDs. The results indicate that Ta ion irradiation significantly degrades the performance of GaN SBDs, as demonstrated by a substantial increase in both forward and reverse leakage currents. Experimental observations reveal that irradiation induces the formation of a defect level positioned at 0.15 eV below the conduction band edge (E_C−0.15 eV). This defect efficiently captures carriers within the n−GaN layer, resulting in a significant carrier removal effect with a removal rate of 1.4 × 10⁷ cm^-1. Furthermore, irradiation induces a damage cascade mechanism along latent tracks, promoting the formation of leakage paths within the device. The damage cascades along the latent tracks represent the primary damage mechanism of Ta ion irradiation, a finding that is further supported by SRIM simulations and cross-sectional high-resolution transmission electron microscopy images. The findings provide valuable insights into the degradation mechanisms of GaN-based devices under Ta ion irradiation and contribute to the advancement of high-frequency GaN SBDs for space applications.