There are advantages in the use of quantum computing in the elaboration of attacks on certain pseudorandom generators when compared with analogous attacks using classical computing. This paper presents a polynomial time quantum attack on the Blum–Micali generator, which is considered secure against threats from classical computers. The proposed attack uses a Grover inspired procedure together with the quantum discrete logarithm, and is able to recover previous and future outputs of the generator under attack, thereby completely compromising its unpredictability. The attack can also be adapted to other generators, such as Blum–Micali generators with multiple hard-core predicates and generators from the Blum–Micali construction, and also to scenarios where the requirements on the bits are relaxed. Such attacks represent a threat to the security of the pseudorandom generators adopted in many real-world cryptosystems.
There are advantages in the use of quantum computing in the elaboration of attacks on certain pseudorandom generators when compared with analogous attacks using classical computing. This paper presents a polynomial time quantum attack on the Blum–Micali generator, which is considered secure against threats from classical computers. The proposed attack uses a Grover inspired procedure together with the quantum discrete logarithm, and is able to recover previous and future outputs of the generator under attack, thereby completely compromising its unpredictability. The attack can also be adapted to other generators, such as Blum–Micali generators with multiple hard-core predicates and generators from the Blum–Micali construction, and also to scenarios where the requirements on the bits are relaxed. Such attacks represent a threat to the security of the pseudorandom generators adopted in many real-world cryptosystems.
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.
Contemporary cryptographic algorithms are resistant to the strongest threats to cybersecurity and high-profile cyber-attacks. In recent times, information security scientists and researchers had developed various cryptographic schemes that defeated attacks using the most sophisticated (in terms of processor speed) classical computer. However, this resistance will soon erode with the arrival of quantum computers. In this paper, we profiled quantum computers and quantum algorithms based on their widely believed threat against currently secure cryptographic primitives. We found that Grover’s and Shor’s quantum-based algorithms actually pose a threat to the continued security of symmetric cryptosystems (e.g. 128-bit AES) and asymmetric (public key) cryptosystems (e.g. RSA, Elgamal, elliptic curve Diffie Hellman (ECDH), etc.) respectively.We discovered that the source of the algorithms’ cryptanalytic power against the current systems, stems from the fact that they (Grover and Shor) both equipped their respective algorithms with a quantum circuit component that can execute the oracle in parallel by applying a single circuit to all possible states of an n-qubit input. With this exponential level of processing characteristic of quantum computers and quantum-based algorithms, it is easy for the current cryptosystems to be broken since the algorithms can existentially solve the underlying mathematical problems such as integer factorization, discrete logarithm problem and elliptic curve problem, which formed the basis of the security of the affected cryptosystems. Based on this realization and as part of our readiness for a post quantum era, we explored other mathematical structures (lattices, hashes, codes, isogenies, high entropy-based symmetric key resistance, and multivariate quadratic problems) whose hardness could surpass the cryptanalytic nightmare posed by quantum computers and quantum-based algorithms. Our contribution is that, based on the findings of this research work, we can confidently assert that all hope is not lost for organizations heavily relying on protocols and applications like HTTPS, TLS, PGP, Bitcoin, etc., which derived their security from the endangered cryptosystems.
Quantum computing is a transformational technology once implemented, capable of addressing problems far beyond the capacity of classical computers. But this progress is also a real challenge to the core of today's modern security. Traditional cryptographic algorithms, such as those based on RSA, ECC, and Diffie-Hellman key exchange, are based on the computational hardness of problems such as prime factorization and discrete logarithms that quantum algorithms solve in polynomial time. As a particular research interesting example, with Shor's Algorithm one can factorize large numbers efficiently, rendering insecure the majority of public key cryptosystems used nowadays. This urgently demands a reevaluation of existing encryption schemes in the context of a post-quantum world. In this paper, we take a closer look at the threats that quantum computers pose to classical security infrastructure including encryption scheme and explore the impact that quantum computation can have on current cryptographic schemes. It calculates the cost in terms of symmetric and asymmetric security, accounting for effects of both Shor's and Grover's algorithms. Symmetric key systems such as AES are also harder hit—Grover's algorithm can give only a quadratic speedup here—but they do need to double key sizes for a sufficient level of post-quantum security. In reaction to those threats, the paper investigates nextgeneration post-quantum cryptographic (PQC) solutions resistant to quantum cryptanalysis. Lattice-based cryptosystems, hash-based signature schemes, multivariate polynomial systems, and code-based cryptosystems are some of the candidates that are being considered in international standardization work, including especially at NIST. In this paper, we compare those alternatives for security, performance, scalability, and feasibility of implementation in real system. An important aspect of this contribution is a comparative study of traditional and post-quantum cryptographic protocols in the context of a number of cybersecurity applications, including secure communications, blockchain networks and IoT contexts. It also covers the quantum readiness timeline and transitional issues, such as backward compatibility, standardization lag and the associated increased computational overhead. Through a mitigated risk evaluation and cryptanalytic attack simulation based on quantum-inspired algorithms, this analysis emphasizes the need to prepare ourselves against quantum-induced security issues. It provides strategic guidance to organizations as they plan for the post-quantum future, stressing cryptographic agility, hybrid encryption models and real-time threat monitoring. Ultimately, the results of this work add to the worldwide conversation on establishing secure systems within the digital age of quantum computing and recommend proactive migration plans for the integrity, confidentiality, and trust one should have in the future cyber world.
The advent of quantum computing poses an existential threat to classical cryptographic systems. Shor’s algorithm (1994) can factor large integers and compute discrete logarithms in polynomial time, breaking widely used schemes like RSA, ECC, and Diffie-Hellman. This paper surveys the state-of-the-art in quantum cryptanalysis, examining its impact on symmetric and asymmetric cryptography, recent progress in quantum attacks, and defenses via post-quantum cryptography (PQC). We analyze key quantum algorithms (Shor’s, Grover’s), their real-world feasibility given current hardware (NISQ-era limitations), and emerging PQC standards (NIST’s CRYSTALS-Kyber, Dilithium). We also discuss novel attack vectors (e.g., hybrid quantum-classical cryptanalysis) and future research directions.
ABSTRACT The rapid advancement of quantum computing poses a serious threat to classical authentication mechanisms that rely on computational hardness assumptions and software-based randomness. Traditional authentication systems such as passwords, one-time passwords (OTPs), and public-key cryptography depend heavily on pseudorandom number generators (PRNGs) and classical cryptographic algorithms, many of which are vulnerable to future quantum attacks. This paper proposes and analyzes a Hybrid Post-Quantum Secure Authentication system using Quantum-Generated One-Time Tokens (Q-OTT). The proposed approach combines true quantum randomness obtained from Quantum Random Number Generators (QRNGs) with post-quantum cryptographic (PQC) algorithms for token protection and verification. A detailed comparison between classical authentication systems and the hybrid Q-OTT approach is presented in terms of randomness, security, entropy, and quantum resistance. The study demonstrates that hybrid Q-OTT systems offer significantly enhanced security against both classical and quantum adversaries, at the cost of moderate infrastructure requirements. Keywords Post-Quantum Cryptography, Quantum Random Number Generator, One-Time Token, Authentication Systems, Quantum Security, Hybrid Authentication