Notice and Invitation Oral Defense of Doctoral Dissertation The Volgenau School of Engineering, George Mason University Kimia Zamiri Azar Bachelor of Science, K. N. Toosi University of Technology, 2013 Master of Science, Shahid Beheshti University, 2015 “VULNERABILITY ASSESSMENT OF LOGIC LOCKING TECHNIQUES: TOWARDS NEXT GENERATION ATTACKS ON LOGIC LOCKING” Tuesday, June 1, 2021, 10:00 AM Zoom Meeting Link: https://gmu.zoom.us/j/97080445863 All are invited to attend. Committee Dr. Avesta Sasan, Chair Dr. Bijan Jabbari Dr. Khaled Khasawneh Dr. Behzad Esmaeili Abstract: The increasing cost of integrated circuits (IC) manufacturing has forced many design houses to become fabless. Outsourcing the stages of the manufacturing supply chain to the third-party facilities has introduced multiple forms of security threats. To combat these threats, logic locking introduces the process of hiding the correct functionality of a circuit using key-programmable logic gates. However, the introduction of the satisfiability (SAT) attack has undermined the effectiveness of many existing logic locking solutions. This dissertation, after showing the shortcomings and limitations of the SAT attack, introduces the newer and stronger attack approaches with much more capabilities and performance compared to the existing ones. It introduces the satisfiability modulo theory (SMT) attack, in which the adversary has the capability of modeling non-Boolean logic locking mechanisms using theory solvers. SMT attack is the first of its kind that can model non-Boolean characteristics of the circuit. Then, we introduce the neural network guided SAT (NNgSAT) attack that exploits the benefit of a message passing neural network (MPNN) to reduce the complexity of the de-obfuscation model, especially when complex structures, such as routing modules and multipliers, are parts of the logic locked circuits. In general, this thesis aims to provide an assessment of the capabilities and limitations of the existing studies on logic locking, with more concentration on attack mechanisms. By introducing newer and stronger approaches, this thesis also opens new directions for the designers to evaluate the security of the designs using more appropriate and well-formulated mechanisms, leading to stronger and more reliable design and implementation with enhanced security.