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Logic encryption, a method to lock a circuit from unauthorized use unless the correct key is provided, is the most important technique in hardware IP protection. However, with the discovery of the SAT attack, all traditional logic encryption algorithms are broken. New algorithms after the SAT attack are all vulnerable to structural analysis unless a provable obfuscation is applied to the locked circuit. But there is no provable logic obfuscation available, in spite of some vague resorting to logic resynthesis. In this paper, we formulate and discuss a trilemma in logic encryption among locking robustness, structural security, and encryption efficiency, showing that pre-SAT approaches achieve only structural security and encryption efficiency, and post-SAT approaches achieve only locking robustness and encryption efficiency. There is also a dilemma between query complexity and error number in locking. We first develop a theory and solution to the dilemma in locking between query complexity and error number. Then, we provide a provable obfuscation solution to the dilemma between structural security and locking robustness. We finally present and discuss some results towards the resolution of the trilemma in logic encryption.
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DK Lock: Dual Key Logic Locking Against Oracle-Guided Attacks
The semiconductor industry must deal with different hardware threats like piracy and overproduction as a result of outsourcing manufacturing. While there are many proposals to lock the circuit using a global protected key only known to the designer, there exist numerous oracle-guided attacks that can examine the locked netlist with the assistance of an activated IC and extract the correct key. In this paper, by adopting a low-overhead structural method, we propose DK Lock, a novel Dual Key locking method that securely protects sequential circuits with two different keys that are applied to one set of key inputs at different times. DK Lock structurally adds an activation phase to the sequential circuit, and a correct key must be applied for several cycles to exit this phase. Once the circuit has been successfully activated, a new functional key must be applied to the same set of inputs to resume normal operation. DK Lock opens up new avenues for hardware IP protection by simultaneously refuting the single static key assumption of the existing attacks and overcoming the state explosion problem of state-of-the-art sequential logic locking methods. Our experiments confirm that DK Lock maintains a high degree of security with reasonable power and area overheads.
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- Award ID(s):
- 2245247
- PAR ID:
- 10490352
- Publisher / Repository:
- IEEE
- Date Published:
- Journal Name:
- Proceedings of International Symposium on Quality Electronic Design (ISQED)
- ISBN:
- 979-8-3503-3475-3
- Page Range / eLocation ID:
- 1 to 7
- Format(s):
- Medium: X
- Location:
- San Francisco, CA, USA
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/ISQED57927.2023.10129368
