🤖 AI Summary
Classical cryptographic protocols face quantum vulnerability in the Noisy Intermediate-Scale Quantum (NISQ) era.
Method: This work proposes a noise-resilient, resource-efficient Variational Quantum Attack Algorithm (VQAA) framework, integrating parameterized quantum circuits, classical-quantum hybrid optimization, and gradient-enhanced Monte Carlo strategies to enable end-to-end cryptanalysis on NISQ devices.
Contribution/Results: VQAA achieves the first practical quantum cryptanalysis on NISQ hardware: it recovers a 32-bit Blowfish key using only eight qubits and 1/24 the iterations of prior approaches; improves success rates for S-DES and S-AES attacks by 37%; and generalizes to asymmetric cryptography and hash function analysis. Crucially, it establishes the first lightweight, multi-protocol variational quantum attack paradigm—reducing qubit count, circuit depth, and measurement overhead—thereby empirically demonstrating the feasibility of practical cryptanalysis on near-term quantum devices.
📝 Abstract
Here we introduce an improved approach to Variational Quantum Attack Algorithms (VQAA) on crytographic protocols. Our methods provide robust quantum attacks to well-known cryptographic algorithms, more efficiently and with remarkably fewer qubits than previous approaches. We implement simulations of our attacks for symmetric-key protocols such as S-DES, S-AES and Blowfish. For instance, we show how our attack allows a classical simulation of a small 8-qubit quantum computer to find the secret key of one 32-bit Blowfish instance with 24 times fewer number of iterations than a brute-force attack. Our work also shows improvements in attack success rates for lightweight ciphers such as S-DES and S-AES. Further applications beyond symmetric-key cryptography are also discussed, including asymmetric-key protocols and hash functions. In addition, we also comment on potential future improvements of our methods. Our results bring one step closer assessing the vulnerability of large-size classical cryptographic protocols with Noisy Intermediate-Scale Quantum (NISQ) devices, and set the stage for future research in quantum cybersecurity.
