While logic locking has been extensively studied as a countermeasure against integrated circuit (IC) supply chain threats, recent research has shifted toward reconfigurable-based redaction techniques, e.g., LUT- and eFPGA-based schemes. While these approaches raise the bar against attacks, they incur substantial overhead, much of which arises not from genuine functional reconfigurability need, but from artificial complexity intended solely to frustrate reverse engineering (RE). As a result, fabrics are often underutilized, and security is achieved at disproportionate cost. This paper introduces NuRedact, the first full-custom eFPGA redaction framework that embraces architectural non-uniformity to balance security and efficiency. Built as an extension of the widely adopted OpenFPGA infrastructure, NuRedact introduces a three-stage methodology: (i) custom fabric generation with pin-mapping irregularity, (ii) VPR-level modifications to enable non-uniform placement guided by an automated Python-based optimizer, and (iii) redaction-aware reconfiguration and mapping of target IP modules. Experimental results show up to 9x area reduction compared to conventional uniform fabrics, achieving competitive efficiency with LUT-based and even transistor-level redaction techniques while retaining strong resilience. From a security perspective, NuRedact fabrics are evaluated against state-of-the-art attack models, including SAT-based, cyclic, and sequential variants, and show enhanced resilience while maintaining practical design overheads.

翻译：尽管逻辑锁定作为应对集成电路（IC）供应链威胁的对策已得到广泛研究，但近期研究已转向基于可重构架构的编辑技术，例如基于查找表（LUT）和嵌入式现场可编程门阵列（eFPGA）的方案。虽然这些方法提高了攻击门槛，但它们带来了显著的开销，其中大部分并非源于实际功能可重构需求，而是来自仅为阻碍逆向工程（RE）而人为引入的复杂性。这导致硬件架构常未被充分利用，且安全性的实现成本不成比例。本文提出NuRedact，首个采用架构非均匀性设计以平衡安全性与效率的全定制eFPGA编辑框架。作为广泛采用的OpenFPGA基础设施的扩展，NuRedact引入三阶段方法：（i）生成具有引脚映射不规则性的定制硬件架构；（ii）在VPR层级进行修改，通过基于Python的自动优化器实现非均匀布局；（iii）面向目标IP模块进行编辑感知的重配置与映射。实验结果表明，与传统均匀架构相比，NuRedact可实现高达9倍的面积缩减，在保持强韧性的同时，其效率与基于LUT乃至晶体管层级的编辑技术相当。从安全视角评估，NuRedact架构在应对包括基于SAT、循环及时序变体在内的先进攻击模型时展现出更强的抵御能力，同时维持了实际的设计开销。