Cyclic logic locking is a cutting-edge hardware security method developed to defend against SAT Attack. It introduces cycles into the original circuit, which can cause the circuit to either get trapped in an endless loop or generate incorrect outputs if an incorrect key is used. Recently, a new cyclic logic locking method called LOOPLock 2.0 was proposed. Its primary feature is that the circuit retains its cyclic structure regardless of whether the correct key vector is applied or not. However, LOOPLock 2.0 can still be successfully attacked using locking structure analysis in the state-of-the-art. As a result, this paper presents a more robust cyclic logic locking approach LOOPLock 3.0 to counteract state-of-the-art attacks. The experimental results validate the effectiveness of the proposed approach.

Cyclic logic locking is a new type of SAT-resistant techniques in hardware security. Recently, LOOPLock 2.0 was proposed, which is a cyclic logic locking method creating cycles deliberately in the locked circuit to resist SAT Attack, CycSAT, BeSAT, and Removal Attack simultaneously. The key idea of LOOPLock 2.0 is that the resultant circuit is still cyclic no matter the key vector is correct or not. This property refuses attackers and demonstrates its success on defending against attackers. In this paper, we propose an unlocking approach to LOOPLock 2.0 based on structure analysis and SAT solvers. Specifically, we identify and remove non-combinational cycles in the locked circuit before running SAT solvers. The experimental results show that the proposed unlocking approach is promising.

LOOPLock is the state-of-the-art cyclic logic locking method in hardware security. LOOPLock is able to invalidate SAT Attack, Removal Attack, and CycSAT simultaneously by introducing two types of cycle pairs in a circuit. In this work, we analyze LOOPLock’s locking mechanism and propose an attacking approach based on locking structure analysis. Furthermore, to defend the new attack, we propose LOOPLock 2.0, which strengthens the original cyclic logic locking method—LOOPLock. Experimental results show the efficiency and effectiveness of the proposed attacking approach to LOOPLock and the high defense capability of LOOPLock 2.0.

Logic equivalence checking is a critical task in the ASIC design flow. Due to the rapid development in nanotechnology-based devices, an efficient implementation of multivalued logic becomes practical. As a result, many synthesis algorithms for ternary logic were proposed. In this paper, we bring out an equivalence checking framework based on multivalued logic exploiting the modern SAT solvers. Furthermore, a structural conflict-driven clause learning (SCDCL) technique is also proposed to accelerate the SAT solving process. The SCDCL algorithm deploys some strategies to cut off the search space for SAT algorithms. The experimental results show that the proposed SCDCL technique saves 42% CPU time from SAT solvers on average over a set of industrial benchmarks.

This paper describes a music rhythm game called AutoRhythm, which can automatically generate the hit time for a rhythm game from a given piece of music, and identify user-defined percussions in real time when a user is playing the game. More specifically, AutoRhythm can automatically generate the hit time of the given music, either locally or via server-based computation, such that users can use the user-supplied music for the game directly. Moreover, to make the rhythm game more realistic, AutoRhythm allows users to interact with the game via any objects that can produce percussion sound, such as a pen or a chopstick hitting on the table. AutoRhythm can identify the percussions in real time while the music is playing. The identification is based on the power spectrum of each frame of the recording which combines percussions and playback music. Based on a test dataset of 12 recordings (with 2455 percussions of 4 types), our experiment indicates an F-measure of 96.79%, which is satisfactory for the purpose of the game. The flexibility of being able to use any user-supplied music for the game and to identify user-defined percussions from any objects available at hand makes the game innovative and unique of its kind.