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.

翻译：本文提出了一种改进的变分量子攻击算法（VQAA），用于针对加密协议。我们的方法能够以显著少于先前方法的量子比特数量，更高效地对知名加密算法实施鲁棒量子攻击。我们对对称密钥协议（如S-DES、S-AES和Blowfish）进行了攻击模拟。例如，我们展示了该攻击如何通过经典模拟一个8量子比特的小型量子计算机，以比暴力攻击少24倍的迭代次数，找出一个32位Blowfish实例的密钥。我们的研究还显示，对于轻量级密码（如S-DES和S-AES），攻击成功率有所提升。此外，我们还讨论了超越对称密钥密码的进一步应用，包括非对称密钥协议和哈希函数。同时，我们也评论了未来对方法进行改进的潜在方向。我们的成果为利用含噪中等规模量子（NISQ）设备评估大规模经典加密协议的脆弱性迈进了重要一步，并为量子网络安全领域的未来研究奠定了基础。