Logic locking is a hardware security technique to intellectual property (IP) against security threats in the IC supply chain, especially untrusted fabs. Such techniques incorporate additional locking circuitry within an IC that induces incorrect functionality when an incorrect key is provided. The amount of error induced is known as the effectiveness of the locking technique. "SAT attacks" provide a strong mathematical formulation to find the correct key of locked circuits. In order to achieve high SAT resilience(i.e. complexity of SAT attacks), many conventional logic locking schemes fail to inject sufficient error into the circuit. For example, in the case of SARLock and Anti-SAT, there are usually very few (or only one) input minterms that cause any error at the circuit output. The state-of-the-art stripped functionality logic locking (SFLL) technique introduced a trade-off between SAT resilience and effectiveness. In this work, we prove that such a trade-off is universal in logic locking. In order to attain high effectiveness of locking without compromising SAT resilience, we propose a novel logic locking scheme, called Strong Anti-SAT (SAS). In addition to SAT attacks, removal-based attacks are also popular against logic locking. Based on SAS, we propose Robust SAS (RSAS) which is resilient to removal attacks and maintains the same SAT resilience and as effectiveness as SAS. SAS and RSAS have the following significant improvements over existing techniques. (1) SAT resilience of SAS and RSAS against SAT attack is not compromised by increase in effectiveness. (2) In contrast to prior work focusing solely on the circuit-level locking impact, we integrate SAS-locked modules into a processor and show that SAS has a high application-level impact. (3) Our experiments show that SAS and RSAS exhibit better SAT resilience than SFLL and have similar effectiveness.
翻译:逻辑锁定是知识产权的硬件安全技术(IP),可以防止IC供应链中的安全威胁,特别是不受信任的外衣。这种技术包括了在IC内增加锁定电路,在提供错误的密钥时导致不正确的功能。错误的数量被称为锁定技术的有效性。“SAT袭击”提供了强大的数学公式,以找到锁定电路的正确关键。为了实现高SAT复原力(即SAT袭击的复杂性),许多常规逻辑锁定计划未能将足够的错误注入IC供应链。例如,SARLock和反SAT,在IC内增加锁电路电路,通常很少有(或只有一个)输入条件,造成不正确的功能。“卫星袭击”是一种先进的数学锁定技术,在SAT的弹性电路中找到正确的关键钥匙。在逻辑锁定中,我们证明这样的交易是普遍的。为了在不破坏SAT的适应能力的情况下实现高度的升级,我们建议一种新的逻辑锁定计划,在SASSAS的电路运和SAS的电路基系统攻击中显示一个强大的逻辑定位系统。