Paper 2016/590

Mitigating SAT Attack on Logic Locking

Yang Xie and Ankur Srivastava


Logic locking is a technique that has been proposed to protect outsourced IC designs from piracy and counterfeiting by untrusted foundries. It can hide the functionality of an IC by inserting key-controlled logic gates into the original design. The locked IC preserves the correct functionality only when a correct key is provided. Recently, the security of logic locking is threatened by a new type of attack called satisfiability checking (SAT) based attack, which can decipher the correct key of most logic locking techniques within a few hours [11] even for reasonably large number of keys. This type of attack iteratively solves SAT formulas which progressively eliminate the incorrect keys till the circuit unlocked. In this paper, we present a specially designed circuit block (referred to as Anti-SAT block) to thwart the SAT attack. We show that the number of SAT attack iterations to reveal the correct key in a circuit comprising an Anti-SAT block is an exponential function of the key-size thereby making the SAT attack computationally infeasible. This is a substantial result because a) we illustrate how to construct the functionality of the Anti- SAT block and b) using a mathematically rigorous approach to prove that if chosen correctly, the Anti-SAT block makes SAT attack computationally infeasible (exponential in key-size). Moreover, through our experiments, we illustrate the effectiveness of our approach to securing modern chips fabricated in untrusted foundries.

Available format(s)
Publication info
Published by the IACR in CHES 2016
Logic LockingSAT AttackHardware IP Protection
Contact author(s)
yangxie @ umd edu
ankurs @ umd edu
2016-06-06: received
Short URL
Creative Commons Attribution


      author = {Yang Xie and Ankur Srivastava},
      title = {Mitigating {SAT} Attack on Logic Locking},
      howpublished = {Cryptology ePrint Archive, Paper 2016/590},
      year = {2016},
      note = {\url{}},
      url = {}
Note: In order to protect the privacy of readers, does not use cookies or embedded third party content.