Protecting Quantum Circuits Through Compiler-Resistant Obfuscation

TL;DR

The paper addresses protecting intellectual property in quantum circuits by introducing a compiler-resistant obfuscation method based on randomized U3 basis transformations that preserve functionality. It details a four-phase workflow (input parsing, basis generation, gate transformation, circuit reconstruction) and demonstrates semantic fidelity above 93% with negligible runtime overhead in QASM/Qiskit AER simulations. The approach yields gates that appear as opaque unitary blocks to compilers, providing robust compiler resistance, while analyses of black-box and white-box threat models quantify the security guarantees. Across a diverse set of circuits, including QAOA and Shor-like algorithms, the method proves practical for secure quantum software deployment, with potential application to cloud-based quantum computing.

Abstract

Quantum circuit obfuscation is becoming increasingly important to prevent theft and reverse engineering of quantum algorithms. As quantum computing advances, the need to protect the intellectual property contained in quantum circuits continues to grow. Existing methods often provide limited defense against structural and statistical analysis or introduce considerable overhead. In this paper, we propose a novel quantum obfuscation method that uses randomized U3 transformations to conceal circuit structure while preserving functionality. We implement and assess our approach on QASM circuits using Qiskit AER, achieving over 93\% semantic accuracy with minimal runtime overhead. The method demonstrates strong resistance to reverse engineering and structural inference, making it a practical and effective approach for quantum software protection.

Figures (12)

• Figure 1: Workflow of the proposed quantum circuit obfuscation using U3-conjugation. The process begins with a QASM circuit, applies a randomized basis transformation, transforms each gate, and restores the original basis to produce an obfuscated circuit with preserved functionality.
• Figure 2: Diagram of the conjugation process $U^{\dagger} \cdot G \cdot U$ for a single-qubit gate (Hadamard) and a multi-qubit gate (CNOT). This figure illustrates the underlying matrix operations and does not imply additional quantum gates or circuit depth. The result of this matrix multiplication ($U^{\dagger} \cdot G \cdot U$) is encapsulated as a single, opaque UnitaryGate object, thereby incurring no space overhead in the quantum circuit.
• Figure 3: Matrix-level transformation of a Hadamard gate using U3 conjugation. The functionality remains unchanged due to the inverse transformation restoring the original gate.
• Figure 4: Matrix-level transformation of a CNOT gate using U3 conjugation, with the Kronecker product scaling the basis for two qubits.
• Figure 5: MaxCut graph corresponding to the 5-node QAOA circuit.