Recent rank-based attacks have reduced the security of Rainbow below the security requirements set out by NIST by speeding up repeated kernel finding operations using classical mathematics techniques. If quantum algorithms are applied to perform these repeated operations, the rank-based attacks may be more threatening and could dramatically lower the security level of Rainbow. In this paper, we propose a novel MinRank attack called Q-rMinRank attack, the first quantum approach to the key recovery attacks on Rainbow. By designing quantum circuits that can find the kernel, we achieved quadratic speedup for the MinRank attack to recover the private keys of Rainbow. We show that even the parameter set V of Rainbow does not meet the 128-bit security level, the minimum security requirement through our Q-rMinRank attack. It means that Rainbow is no longer secure in quantum computing environments.
Recent rank-based attacks have reduced the security of Rainbow below the security requirements set out by NIST by speeding up repeated kernel finding operations using classical mathematics techniques. If quantum algorithms are applied to perform these repeated operations, the rank-based attacks may be more threatening and could dramatically lower the security level of Rainbow. In this paper, we propose a novel MinRank attack called Q-rMinRank attack, the first quantum approach to the key recovery attacks on Rainbow. By designing quantum circuits that can find the kernel, we achieved quadratic speedup for the MinRank attack to recover the private keys of Rainbow. We show that even the parameter set V of Rainbow does not meet the 128-bit security level, the minimum security requirement through our Q-rMinRank attack. It means that Rainbow is no longer secure in quantum computing environments.
Abstract Recent rank-based attacks have reduced the security of Rainbow, which is one of the multi-layer UOV signatures, below the NIST security requirements by speeding up iterative kernel-finding operations using classical mathematics techniques. If quantum algorithms are applied to perform these iterative operations, the rank-based attacks may be more threatening to multi-layer UOV, including Rainbow. In this paper, we propose a quantum rectangular MinRank attack called the Q-rMinRank attack, the first quantum approach to key recovery attacks on multi-layer UOV signatures. Our attack is a general model applicable to multi-layer UOV signature schemes, and in this paper, we provide examples of its application to Rainbow and the Korean TTA standard, HiMQ. We design two quantum oracle circuits to find the kernel in consideration of the depth-width trade-off of quantum circuits. One is to reduce the width of the quantum circuits using qubits as a minimum, and the other is to reduce the depth using parallelization instead of using a lot of qubits. By designing quantum circuits to find kernels with fewer quantum resources and complexity by adding mathematical techniques, we achieve quadratic speedup for the MinRank attack to recover the private keys of multi-layer UOV signatures. We also estimate quantum resources for the designed quantum circuits and analyze quantum complexity based on them. The width-optimized circuit recovers the private keys of Rainbow parameter set V with only 1089 logical qubits. The depth-optimized circuit recovers the private keys of Rainbow parameter set V with a quantum complexity of 2174 2 174 , which is lower than the complexity of 2221 2 221 recovering the secret key of AES-192, which provides the same security level as parameter set III.
Due to their simple security assessments, permutation-based pseudo-random functions (PRFs) have become widely used in cryptography. It has been shown that PRFs using a single n-bit permutation achieve n/2 bits of security, while those using two permutation calls provide 2n/3 bits of security in the classical setting. This paper studies the security of permutation-based PRFs within the Q1 model, where attackers are restricted to classical queries and offline quantum computations. We present improved quantum-time/classical-data tradeoffs compared with the previous attacks. Specifically, under the same assumptions/hardware as Grover’s exhaustive search attack, i.e. the offline Simon algorithm, we can recover keys in quantum time Õ(2n/3), with O(2n/3) classical queries and O(n2) qubits. Furthermore, we enhance previous superposition attacks by reducing the data complexity from exponential to polynomial, while maintaining the same time complexity. This implies that permutation-based PRFs become vulnerable when adversaries have access to quantum computing resources. It is pointed out that the above quantum attack can be applied to several cryptographic schemes, including PDMMAC and pEDM, as well as general instantiations like XopEM, EDMEM, EDMDEM, and others.
The rapid advancement of quantum computing threatens to undermine the security foundations of modern cryptographic systems, particularly those based on integer factorization and discrete logarithm problems. Algorithms such as Shor’s and Grover’s promise exponential or quadratic speedups, rendering RSA, ECC, and certain symmetric schemes vulnerable within the next decade. This paper presents a simulated evaluation of classical cryptographic algorithms against quantum attacks, followed by a performance assessment of post-quantum cryptographic (PQC) schemes—specifically lattice-based, hash-based, and code-based algorithms. A testing framework was developed using a quantum simulator (Qiskit) and a classical benchmarking environment to model potential attack timelines and measure computational efficiency. Results demonstrate that RSA-2048 can be theoretically broken within 8 hours on a 4000-qubit fault-tolerant quantum processor, while ECC-P256 succumbs in less than 4 hours. In contrast, lattice-based schemes such as CRYSTALS-Kyber resisted quantum simulation attacks, maintaining equivalent classical security levels with only a 27% performance overhead. The study also analyzes the trade-offs between key size, encryption/decryption speed, and resistance to quantum attacks. Our findings emphasize the urgent need for migration to NIST-recommended PQC algorithms and provide a decision-support matrix for selecting suitable replacements in government and enterprise systems.
Long, human-generated passwords pose significant challenges to both classical and quantum attacks due to their irregular structure and large search space. In this work, we propose an enhanced classical-quantum hybrid attack specifically designed for this scenario. Our approach constructs rainbow tables using dictionary-based password generation augmented with transformation rules that better capture real-world user behavior. These tables are organized into buckets, enabling faster lookup and reduced space complexity. For the search within each bucket, we employ a distributed exact variant of Grover's algorithm. This method provides deterministic success and significantly lower circuit depth, enhancing robustness against noise-particularly depolarizing errors common in near-term quantum devices. Overall, our hybrid framework improves the efficiency and practicality of password recovery for long, human-readable passwords in realistic adversarial settings.
It has been established that quantum algorithms can solve several key cryptographic problems more efficiently than classical computers. As progress continues in the field of quantum computing it is important to understand the risks they pose to deployed cryptographic systems. Here we focus on one of these risks - quantum key-recovery attacks against ideal ciphers. Specifically, we seek to model the risk posed by an economically motivated quantum attacker who will choose to run a quantum key-recovery attack against an ideal cipher if the cost to recover the secret key is less than the value of the information at the time when the key-recovery attack is complete. In our analysis we introduce the concept of a quantum cipher circuit year to measure the cost of a quantum attack. This concept can be used to model the inherent tradeoff between the total time to run a quantum key recovery attack and the total work required to run said attack. Our model incorporates the time value of the encrypted information to predict whether any time/work tradeoff results in a key-recovery attack with positive utility for the attacker. We make these predictions under various projections of advances in quantum computing. We use these predictions to make recommendations for the future use and deployment of symmetric key ciphers to secure information against these quantum key-recovery attacks. We argue that, even with optimistic predictions for advances in quantum computing, 128 bit keys (as used in common cipher implementations like AES-128) provide adequate security against quantum attacks in almost all use cases.
The paper identifies and analyzes attacks aimed at Rainbow post-quantum electronic signature cryptanalysis. Today, due to advances in the quantum computers development, the need to present new standards for electronic signatures resistant to both quantum and classical cryptanalysis arisen. To solve the lack of such electronic signatures, NIST USA is running the NIST PQC competition. As part of this competition some electronic signatures designed to resist quantum cryptanalysis were presented, including Rainbow electronic signature. CZ-Rainbow and the compressed Rainbow algorithm were also presented along with the regular Rainbow algorithm. This paper analysis attacks on all three types of electronic signature. The possibility of a quantum attack against the Rainbow electronic signature, as well as the complexity of such an attack, defines the possibility of this electronic signature usage during the post-quantum period.