With the separation of design and manufacture in semiconductor industry, self-designed circuits are exposed to hardware Trojan attacks when they are outsourced to an untrustworthy foundry. Trojans activated by digital logic have gained extensive attention. However, those with analog trigger component remain as a serious issue such as the A2 Trojan. Existing defense against A2 Trojans mainly relies on runtime detection mechanism which needs large monitor hardware overhead and complicated identification/handling software. To address these limitations, this article proposes a built-in structure to accelerate the activation of A2 Trojans, which consists of several composite-logic ring oscillators and a multiple-purpose controller. In addition, two post-fabrication detection schemes named time-division mode-switching (TDMS) and scan-based fault test compatible (SFTC) are proposed. TDMS detection scheme can discover A2 Trojans when running functional patterns by inserting oscillating operations every other cycle. SFTC detection scheme can detect A2 Trojans during scan-based fault test by introducing oscillation before each capture operation. Evaluations across a wide range of A2 Trojans and benchmarks show that our proposal is more power-efficient and area-saving compared with existing monitor structure.

中文翻译：

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基于内置加速结构的A2木马检测新设计策略

随着半导体行业设计与制造的分离，自行设计的电路在外包给不可信的代工厂时容易受到硬件木马攻击。由数字逻辑激活的木马程​​序受到广泛关注。然而，那些带有模拟触发组件的仍然是一个严重的问题，例如 A2 木马。现有针对A2木马的防御主要依赖运行时检测机制，需要大量的监控硬件开销和复杂的识别/处理软件。为了解决这些限制，本文提出了一种内置结构来加速 A2 木马的激活，该结构由多个复合逻辑环形振荡器和一个多用途控制器组成。此外，提出了两种称为时分模式切换（TDMS）和基于扫描的故障测试兼容（SFTC）的制造后检测方案。TDMS检测方案可以通过每隔一个周期插入振荡操作，在运行功能模式时发现A2木马。SFTC 检测方案可以在基于扫描的故障测试期间通过在每次捕获操作之前引入振荡来检测 A2 木马。对广泛的 A2 木马和基准的评估表明，与现有的监视器结构相比，我们的提议更节能、更节省面积。SFTC 检测方案可以在基于扫描的故障测试期间通过在每次捕获操作之前引入振荡来检测 A2 木马。对广泛的 A2 木马和基准的评估表明，与现有的监视器结构相比，我们的提议更节能、更节省面积。SFTC 检测方案可以在基于扫描的故障测试期间通过在每次捕获操作之前引入振荡来检测 A2 木马。对广泛的 A2 木马和基准的评估表明，与现有的监视器结构相比，我们的提议更节能、更节省面积。