Logic locking has emerged as a prominent technique to protect an integrated circuit from piracy, overbuilding, and hardware Trojans. Most of the well-known logic locking techniques are vulnerable to satisfiability (SAT) based attack. Though several SAT-resistant logic locking techniques such as Anti-SAT block (ASB) are reported that increase the time to decipher the secret key, the existing techniques are either vulnerable to signal probability skew (SPS) based removal attack or require significant design overhead. Therefore, a new lightweight ASB design and obfuscation technique is proposed that effectively integrate and obfuscates the ASB in the design to thwart removal attack. We first propose a new ASB design/integration approach that effectively thwarts the structural/functional analysis based removal attack with minimum overhead. Further, we also propose an ASB obfuscation approach that shifts the inverter deep in the circuit using De Morgan's law and replaces an ASB gate with a key-gate to thwart SPS based removal attack. Moreover, a new algorithm is proposed that inserts the ASB in the locked design to achieve desired output corruptibility. Finally, a new INV/BUFF key-gate is proposed that constructs the ASB with reduced overhead over the XOR/XNOR. Experimental evaluation on ISCAS-85 benchmarks shows that our ASB design and obfuscation approaches, on an average, reduce area overhead by 25.5% and 22% respectively, and effectively prevent removal attack without reducing any security.

逻辑锁定已成为保护集成电路免受盗版，过度构建和硬件特洛伊木马程序侵害的重要技术。大多数众所周知的逻辑锁定技术都容易受到基于可满足性（SAT）的攻击。尽管据报导有几种抗SAT的逻辑锁定技术（例如Anti-SAT块（ASB））增加了解密密钥的时间，但是现有技术要么容易受到基于信号概率偏斜（SPS）的移除攻击的攻击，要么需要大量设计开销。因此，提出了一种新的轻量级ASB设计和混淆技术，该技术可以有效地集成和混淆设计中的ASB以阻止删除攻击。我们首先提出一种新的ASB设计/集成方法，以最小的开销有效地挫败基于结构/功能分析的删除攻击。进一步，我们还提出了一种ASB模糊处理方法，该方法使用De Morgan定律将逆变器移入电路深处，并用键控门代替ASB门，以阻止基于SPS的移除攻击。此外，提出了一种新算法，将ASB插入锁定设计中以实现所需的输出可破坏性。最后，提出了一种新的INV / BUFF键门，该键门构造的ASB具有比XOR / XNOR更低的开销。对ISCAS-85基准的实验评估表明，我们的ASB设计和混淆方法平均可分别减少25.5％和22％的区域开销，并在不降低安全性的情况下有效地防止了移除攻击。提出了一种新算法，该算法将ASB插入锁定设计中以实现所需的输出可破坏性。最后，提出了一种新的INV / BUFF键门，该键门构造的ASB具有比XOR / XNOR更低的开销。对ISCAS-85基准的实验评估表明，我们的ASB设计和混淆方法平均可分别减少25.5％和22％的区域开销，并在不降低安全性的情况下有效地防止了移除攻击。提出了一种新算法，该算法将ASB插入锁定设计中以实现所需的输出可破坏性。最后，提出了一种新的INV / BUFF键门，该键门构造的ASB具有比XOR / XNOR更低的开销。对ISCAS-85基准的实验评估表明，我们的ASB设计和混淆方法平均可分别减少25.5％和22％的区域开销，并在不降低安全性的情况下有效地防止了移除攻击。