论文标题

卫星循环逻辑混淆,用于保护制造供应链中的IP

SAT-hard Cyclic Logic Obfuscation for Protecting the IP in the Manufacturing Supply Chain

论文作者

Roshanisefat, Shervin, Kamali, Hadi Mardani, Homayoun, Houman, Sasan, Avesta

论文摘要

针对循环逻辑混淆的最新攻击使用配备一组循环避免条款的满意度求解器。这些循环回避条款是在预处理步骤中生成的,并定义了可以打开或关闭周期的各种关键组合,而无需使电路振荡或状态。在本文中,我们表明,此预处理步骤必须在网络清单中的所有周期上生成循环回避条件,否则,缺失的周期可能会将求解器捕获到无限的循环中,或者用不正确的键使其退出。然后,我们提出了几种技术,通过这些技术,循环的数量随着插入的反馈数量的函数而成倍增加。我们进一步说明,当反馈数量增加时,攻击的预处理步骤将面临复杂性和运行时的指数增加,从而阻止了合理时间内循环回避条款的正确组成。另一方面,如果没有结束预处理,则可满足性求解器所制定的攻击将被卡住或退出,并以不正确的键退出。因此,当实施本文提出的条件下的环状混淆时,它将对基于满意度求解器的攻击构成指数困难的问题。

State-of-the-art attacks against cyclic logic obfuscation use satisfiability solvers that are equipped with a set of cycle avoidance clauses. These cycle avoidance clauses are generated in a pre-processing step and define various key combinations that could open or close cycles without making the circuit oscillating or stateful. In this paper, we show that this pre-processing step has to generate cycle avoidance conditions on all cycles in a netlist, otherwise, a missing cycle could trap the solver in an infinite loop or make it exit with an incorrect key. Then, we propose several techniques by which the number of cycles is exponentially increased as a function of the number of inserted feedbacks. We further illustrate that when the number of feedbacks is increased, the pre-processing step of the attack faces an exponential increase in complexity and runtime, preventing the correct composition of cycle avoidance clauses in a reasonable time. On the other hand, if the pre-processing is not concluded, the attack formulated by the satisfiability solver will either get stuck or exit with an incorrect key. Hence, when the cyclic obfuscation under the conditions proposed in this paper is implemented, it would impose an exponentially difficult problem for the satisfiability solver based attacks.

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