[Cryptech Tech] fyi: Anti-SAT: Mitigating SAT Attack on Logic Locking (wrt untrusted fabs)

[=JeffH]

just a background data point of possible interest...

[ePrint Report] Anti-SAT: Mitigating SAT Attack on Logic Locking
Yang Xie, Ankur Srivastava
http://eprint.iacr.org/2017/761

Logic locking is a technique that's proposed to protect outsourced IC 
designs from piracy and counterfeiting by untrusted foundries. A locked 
IC preserves the correct functionality only when a correct key is 
provided. Recently, the security of logic locking is threatened by a new 
attack called SAT attack, which can decipher the correct key of most 
logic locking techniques within a few hours even for a reasonably large 
key-size. This attack iteratively solves SAT formulas which 
progressively eliminate the incorrect keys till the circuit is unlocked. 
In this paper, we present a circuit block (referred to as Anti-SAT 
block) to enhance the security of existing logic locking techniques 
against the SAT attack. We show using a mathematical proof 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. Besides, we 
address the vulnerability of the Anti-SAT block to various removal 
attacks and investigate obfuscation techniques to prevent these removal 
attacks. More importantly, we provide a proof showing that these 
obfuscation techniques for making Anti-SAT un-removable would not weaken 
the Anti-SAT block's resistance to SAT attack. Through our experiments, 
we illustrate the effectiveness of our approach to securing modern chips 
fabricated in untrusted foundries.