The SAT attack has shown to be efficient against most combinational logic encryption methods. It can be extended to attack sequential logic encryption techniques by leveraging circuit unrolling and model checking methods. However, with no guidance on the number of times that a circuit needs to be unrolled to find the correct key, the attack tends to solve many time-consuming Boolean satisfiability (SAT) and model checking problems, which can significantly hamper its efficiency. In this paper, we introduce Fun-SAT, a functional corruptibility-guided SAT-based attack that can significantly decrease the SAT solving and model checking time of a SAT-based attack on sequential encryption by efficiently estimating the minimum required number of circuit unrollings. Fun-SAT relies on a notion of functional corruptibility for encrypted sequential circuits and its relationship with the required number of circuit unrollings in a SAT-based attack. Numerical results show that Fun-SAT can be, on average, 90x faster than previous attacks against state-of-the-art encryption methods, when both attacks successfully complete before a one-day time-out. Moreover, Fun-SAT completes before the time-out on many more circuits.
翻译:SAT攻击显示,对多数组合逻辑加密方法来说是有效的。它可以通过利用电路解动和模型检查方法,扩大到打击序列逻辑加密技术。然而,如果没有关于电路需要解动以找到正确钥匙的次数的指导,攻击往往会解决许多耗时的布利安卫星卫星卫星和模型检查问题,这些问题会大大妨碍其效率。在本文中,我们引入了Fun-SAT,这是一种功能腐败引导的SAT攻击,通过高效估计电路解动的最低数量,可以大大减少SAT对连续加密攻击的解算和模型检查时间。 Fun-SAT依靠加密连续电路的功能腐败性概念及其与在SAT攻击中所需的电路解动数量的关系。数字结果显示,在一天外的两次攻击成功完成之前,Fun-SAT平均可以比以前对最新加密方法的攻击快90x,而且许多时间都比结束的时间要快。此外,Fun-SAT在很多次的电路外都完成了。