JANUS-HD: Exploiting FSM Sequentiality and Synthesis Flexibility in Logic Obfuscation to Thwart SAT Attack While Offering Strong Corruption
JANUS-HD: Exploiting FSM Sequentiality and Synthesis Flexibility in Logic Obfuscation to Thwart SAT Attack While Offering Strong Corruption
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JANUS-HD：利用逻辑混淆中的 FSM 顺序性和综合灵活性来阻止 SAT 攻击，同时提供强大的破坏性
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发表时间：
2022
期刊：
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通讯作者：
A. Orailoglu
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作者：
Leon Li;A. Orailoglu
逻辑混淆已被提出作为对抗芯片伪造和IP盗版的对策，通过使用密钥控制的锁定机制来混淆电路设计。然而，早期基于密钥门的逻辑混淆技术的广泛输出损坏使它们暴露于有效的SAT攻击。虽然当前的SAT弹性逻辑混淆技术通过提供近乎微不足道的输出损坏成功地破坏了攻击，但它们这样做是以功能和结构保护范围的急剧减少为代价的。在这项工作中，我们提出了JANUS-HD基于新的见解，成功地提供了迄今为止难以实现的目标，同时提高腐败和挫败SAT攻击。JANUS-HD通过用于不同转换的不同FF配置来混淆FSM，其中总体配置设置作为混淆秘密。一个键控汉明距离比较器控制的混淆状态，在最小数量的入口状态，通过自定义图划分算法确定。对固有状态转换模式的依赖将混淆益处扩展到非进入状态，而不暴露任何额外的密钥空间修剪迹线。我们利用状态编码的灵活性和基于等价的FSM转换，使用标准合成工具以低开销生成混淆网表。最后，我们提出了一个扫描链削弱机制，提供不受约束的扫描链访问，同时消除任何关键的跟踪泄漏的扫描模式，从而挫败选择输入攻击的汉明距离比较器。我们通过实验说明，JANUS-HD的混淆范围比最先进的混淆范围提高了45.5倍，建立了第一个具有成本效益的解决方案，可以针对供应链威胁提供广泛但具有攻击弹性的混淆范围。
Logic obfuscation has been proposed as a counter-measure towards chip counterfeiting and IP piracy by obfuscating circuit designs with a key-controlled locking mechanism. However, the extensive output corruption of early key gate based logic obfuscation techniques has exposed them to effective SAT attacks. While current SAT resilient logic obfuscation techniques succeed in undermining the attack by offering near-trivial output corruption, they do so at the expense of a drastic reduction in functional and structural protection scope. In this work, we present JANUS-HD based on novel insights that succeed to deliver the heretofore elusive goal of simultaneously boosting corruptibility and foiling SAT attacks. JANUS-HD obfuscates an FSM through diverse FF configurations for different transitions with the overall configuration setting as the obfuscation secret. A key-controlled Hamming distance comparator controls the obfuscation status at the minimized number of entrance states identified through a custom graph partitioning algorithm. Reliance on the inherent state transition patterns extends the obfuscation benefits to non-entrance states without exposing any additional key space pruning trace. We leverage the flexibility of state encoding and equivalence-based FSM transformations to generate an obfuscated netlist at low overhead using standard synthesis tools. Finally, we present a scan chain crippling mechanism that delivers unfettered scan chain access while eradicating any key trace leakage in the scan mode, thus thwarting chosen-input attacks aimed at the Hamming distance comparator. We illustrate through experiments that JANUS-HD delivers obfuscation scope improvements of up to 45.5x over the state-of-the-art, establishing the first cost-effective solution to offer a broad yet attack-resilient obfuscation scope against supply chain threats.