We call quantum security the area of IT security dealing with scenarios where one or more parties have access to quantum hardware. This encompasses both the fields of post-quantum cryptography (that is, traditional cryptography engineered to be resistant against quantum adversaries), and quantum cryptography (that is, security protocols designed to be natively run on a quantum infrastructure, such as quantum key distribution). Moreover, there exist also hybrid models, where traditional cryptographic schemes are somehow `mixed' with quantum operations in certain scenarios. Even if a fully-fledged, scalable quantum computer has yet to be built, recent results and the pace of research in its realization call for attention, lest we suddenly find ourselves one day with an obsolete security infrastructure. For this reason, in the last two decades research in quantum security has experienced an exponential growth in interest and investments. In this work, we propose the first systematic classification of quantum security scenarios, and for each of them we recall the main tools and results, as well as presenting new ones. We achieve this goal by identifying four distinct quantum security classes, or domains, each of them encompassing the security notions and constructions related to a particular scenario. We start with the class QS0, which is `classical cryptography' (meaning that no quantum scenario is considered), where we present some classical constructions and results as a preliminary step. Regarding post-quantum cryptography, we introduce the class QS1, where we discuss in detail the problems arising when designing a classical cryptographic object meant to be resistant against adversaries with local quantum computing power, and we provide a classification of the possible quantum security reductions in this scenario when considering provable security. Moreover, we present results about the quantum security and insecurity of the Fiat-Shamir transformation (a useful tool used to turn interactive identification schemes into digital signatures), and ORAMs (protocols used to outsource a database in a private way). In respect to hybrid classical-quantum models, in the security class QS2 we discuss in detail the possible scenarios where these scenarios arise, and what a correct formalization should be in terms of quantum oracle access. We also provide a novel framework for the quantum security (both in terms of indistinguishability and semantic security) of secret-key encryption schemes, and we give explicit secure constructions, as well as impossibility results. Finally, in the class QS3 we consider all those cryptographic constructions designed to run natively on quantum hardware. We give constructions for quantum encryption schemes (both in the secret- and public-key scenario), and we introduce transformations for obtaining such schemes by conceptually simpler schemes from the class QS2. Moreover, we introduce a quantum version of ORAM, called quantum ORAM (QORAM), aimed at outsourcing in a private way a database composed of quantum data. In proposing a suitable security model and an explicit construction for QORAMs, we also introduce a technique of independent interest which models a quantum adversary able to extract information from a quantum system without disturbing it `too much'. We believe that the framework we introduce in this work will be a valuable tool for the scientific community in addressing the challenges arising when formalizing sound constructions and notions of security in the quantum world.
We call quantum security the area of IT security dealing with scenarios where one or more parties have access to quantum hardware. This encompasses both the fields of post-quantum cryptography (that is, traditional cryptography engineered to be resistant against quantum adversaries), and quantum cryptography (that is, security protocols designed to be natively run on a quantum infrastructure, such as quantum key distribution). Moreover, there exist also hybrid models, where traditional cryptographic schemes are somehow mixed' with quantum operations in certain scenarios. Even if a fully-fledged, scalable quantum computer has yet to be built, recent results and the pace of research in its realization call for attention, lest we suddenly find ourselves one day with an obsolete security infrastructure. For this reason, in the last two decades research in quantum security has experienced an exponential growth in interest and investments. In this work, we propose the first systematic classification of quantum security scenarios, and for each of them we recall the main tools and results, as well as presenting new ones. We achieve this goal by identifying four distinct quantum security classes, or domains, each of them encompassing the security notions and constructions related to a particular scenario. We start with the class QS0, which is classical cryptography' (meaning that no quantum scenario is considered), where we present some classical constructions and results as a preliminary step. Regarding post-quantum cryptography, we introduce the class QS1, where we discuss in detail the problems arising when designing a classical cryptographic object meant to be resistant against adversaries with local quantum computing power, and we provide a classification of the possible quantum security reductions in this scenario when considering provable security. Moreover, we present results about the quantum security and insecurity of the Fiat-Shamir transformation (a useful tool used to turn interactive identification schemes into digital signatures), and ORAMs (protocols used to outsource a database in a private way). In respect to hybrid classical-quantum models, in the security class QS2 we discuss in detail the possible scenarios where these scenarios arise, and what a correct formalization should be in terms of quantum oracle access. We also provide a novel framework for the quantum security (both in terms of indistinguishability and semantic security) of secret-key encryption schemes, and we give explicit secure constructions, as well as impossibility results. Finally, in the class QS3 we consider all those cryptographic constructions designed to run natively on quantum hardware. We give constructions for quantum encryption schemes (both in the secret- and public-key scenario), and we introduce transformations for obtaining such schemes by conceptually simpler schemes from the class QS2. Moreover, we introduce a quantum version of ORAM, called quantum ORAM (QORAM), aimed at outsourcing in a private way a database composed of quantum data. In proposing a suitable security model and an explicit construction for QORAMs, we also introduce a technique of independent interest which models a quantum adversary able to extract information from a quantum system without disturbing it `too much'. We believe that the framework we introduce in this work will be a valuable tool for the scientific community in addressing the challenges arising when formalizing sound constructions and notions of security in the quantum world.
The emergence of quantum computing has provided new paradigms for cryptography. On the one hand, it poses significant new threats to existing classically cryptographic systems, requiring the community to define new security models that capture what a quantum adversary can do. On the other hand, it gives us new tools to design cryptographic protocols, with weaker assumptions than in the classical world, or even protocols that are impossible classically. In this survey, we first give an overview of new security definitions for classical cryptography, considering quantum adversaries who can either only use local quantum computation (post-quantum security), or even send quantum messages and in particular have access to oracle in superposition (quantum security). We explore these new notions through the examples of commitments, zero-knowledge proofs, encryption, and signatures. Then, we present what is arguably the most famous application of quantum cryptography: quantum key distribution (QKD) protocols that take advantage of unique properties of quantum mechanics to provide secure communication unconditionally. We also explore cryptography beyond QKD, focusing on unclonable cryptography: a family of cryptographic functionalities, built with quantum states, and designed to be resistant to counterfeit by leveraging the “no-cloning” theorem. We examine in particular quantum money, but also the recent notions of unclonable encryption and copy-protection, including related variants. By presenting a comprehensive survey of these topics, this paper aims to provide a thorough understanding of the current landscape and future potential of quantum cryptography.
Abstract It is viewed as revolutionary technology, offering incredible potential in terms of computing power within different scientific and industrial sectors. Quantum computers provide remarkable computing power; however, they also present significant security risks to existing public-key cryptography systems used to secure digital communication, online banking systems, government, medical applications, cloud computing systems, and IoT systems. Security of commonly used encryption schemes like RSA, DH, and ECC depends on mathematical problems that are impossible for classical computers to solve but can be easily resolved with the help of powerful enough quantum computers by using Shor’s algorithm. Furthermore, Grover’s algorithm makes exhaustive search attacks much faster, thus effectively lowering the security level of symmetric encryption schemes since it provides the speed-up for brute-force attacks. Post-Quantum Cryptography (PQC) turned out to be an effective and scalable method to protect digital data from attacks using quantum computing. In contrast to quantum cryptography, which requires a special quantum communication channel, PQC uses classical cryptographic algorithms that cannot be broken down by either classical or quantum computer due to certain mathematical problems. This research paper offers an extensive exploration of post-quantum cryptography through the analysis of the development of quantum computing, weaknesses of current cryptographic techniques, and mathematics behind quantum-resistant algorithms. Moreover, this paper explores the major classes of PQC techniques such as lattice-based, code-based, hash-based, multivariate, and isogeny-based cryptography and provides details about their security and application. Moreover, the report gives an overview of the NIST Post-Quantum Cryptography Standardization Project and analyzes recent standardizations of quantum-proof algorithms to be utilized in future digital infrastructures. Keywords: Post-Quantum Encryption, Quantum Security, Quantum-Proof Public-Key Cryptography, Lattice-Based Security Protocols, ML-KEM Key Encapsulation Mechanism, ML-DSA Digital Signature Algorithm, NIST Post-Quantum Cryptography, Contemporary Cybersecurity, Secure Communications, Cryptographic Algorithms.
Shor’s quantum factoring algorithm and a few other efficient quantum algorithms break many clas-sical crypto-systems. In response, people proposed post-quantum cryptography based on computational problems that are believed hard even for quantum computers. However, security of these schemes against quantum attacks is elusive. This is because existing security analysis (almost) only deals with classical attackers and arguing security in the presence of quantum adversaries is challenging due to unique quan-tum features such as no-cloning. This work proposes a general framework to study which classical security proofs can be restored in the quantum setting. Basically, we split a security proof into (a sequence of) classical security reductions, and investigate what security reductions are “quantum-friendly”. We characterize sufficient conditions such that a classical reduction can be “lifted ” to the quantum setting. We then apply our lifting theorems to post-quantum signature schemes. We are able to show that the classical generic construction of hash-tree based signatures from one-way functions and and a more efficient variant proposed in [BDH11] carry over to the quantum setting. Namely, assuming existence of (classical) one-way functions that are resistant to efficient quantum inversion algorithms, there exists a quantum-secure signature scheme. We note that the scheme in [BDH11] is a promising (post-quantum) candidate to be implemented in practice and our result further justifies it. Actually, to obtain these results, we formalize a simple criteria, which is motivated by many classical proofs in the literature and is straightforward to check. This makes our lifting theorem easier to apply, and it should be useful elsewhere to prove quantum security of proposed post-quantum cryptographic schemes. Finally we demonstrate the generality of our framework by showing that several existing works (Full-Domain hash in the quantum random-oracle model [Zha12b] and the simple hybrid arguments framework in [HSS11]) can be reformulated under our unified framework. 1
Abstract Quantum computing promises unprecedented computational power, posing fundamental threats and offering novel solutions to modern cryptography and cybersecurity. This survey paper reviews the rapidly evolving landscape of quantum-resistant and quantum-native security protocols. By analyzing foundational computational security models and the unique vulnerabilities introduced by quantum algorithms, this work proposes a structured evaluation framework for assessing the robustness of cryptographic systems. Ultimately, this survey highlights the critical transition from classical cryptographic infrastructures to quantum-secure paradigms, ensuring data confidentiality and integrity in the post-quantum era. Keywords: Quantum Computing, Security Protocol, Vulnerabilities 1.Introduction The emergence of quantum computing represents a paradigm shift in both computational physics and information technology. Quantum algorithms, particularly Shor's and Grover's algorithms, inherently challenge the mathematical foundations of classical public-key cryptography. As a result, securing communication channels against quantum-empowered adversaries has become an urgent priority for global infrastructure and national security. The motivation for this survey stems from the immediate need to bridge the gap between theoretical quantum mechanics and applied cybersecurity, ensuring that secure communications can withstand the computational leaps expected in the next decade. The core problem addressed in this paper is the comprehensive evaluation of security protocols under the threat model of a fully scalable quantum computer. The scope encompasses both post-quantum cryptographic (PQC) protocols and inherently quantum protocols, such as those relying on physical quantum states for key distribution. Existing classical approaches are insufficient for two main reasons. First, classical computational security models often rely on mathematical hardness assumptions (like integer factorization) that are rapidly undermined by theoretical quantum algorithms. Second, current software tools for designing secure classical protocols fail to account for quantum state phenomena, such as superposition and entanglement, rendering classical verification methods inadequate for quantum threat models. To address these structural challenges, this paper presents the following contributions: We provide a comprehensive taxonomy of vulnerabilities in both classical and quantum security protocols, mapping specific algorithmic advantages to protocol failure points. We propose a structured, multi-module framework for simulating, attacking, and verifying the security of hybrid quantum-classical cryptographic architectures. 2.Foundations of Classical Protocol Analysis The rigorous analysis of security protocols has traditionally relied on well-defined computational and symbolic models (Toorani, 2016). Researchers have extensively mapped out the taxonomy of attacks on authenticated key exchange (AKE) protocols and password-authenticated key exchange (PAKE) systems, establishing the mathematical groundwork for secure communication. The core idea of these foundational works is to establish provable security bounds that distinguish between information-theoretic and computational security. While this traditional paradigm offers strong mathematical guarantees against classical adversaries, its primary weakness is the failure to incorporate quantum attack vectors into the adversary's capability profile. Our work builds upon these classical models by explicitly injecting quantum algorithmic capabilities into standard protocol verification routines. 2.1.Quantum Algorithm Development and Simulation A significant body of literature focuses on the theoretical development and computational simulation of quantum algorithms capable of compromising or enhancing network security. Academic overviews have formalized algorithms like Grover's and Shor's, demonstrating their theoretical efficiency over classical counterparts in breaking cryptographic primitives. Furthermore, researchers have developed advanced design automation tools, such as decision diagrams, to simulate and verify complex quantum circuits. The strength of these simulation tools lies in their ability to model complex quantum states without requiring expensive physical hardware. However, a notable weakness is that they often abstract away the physical noise and hardware constraints that exist in real-world cryptographic deployments. This survey contextualizes these simulation techniques specifically within the framework of adversarial security testing, bridging theoretical algorithms with practical protocol defense. 3.Physical Implementations and Hardware Considerations Beyond algorithmic theory, the physical realization of quantum states directly impacts the practical security of any quantum protocol. Research into cavity quantum electrodynamics (QED) has demonstrated the complete mathematical construction of fundamental quantum gates, such as the controlled-controlled NOT gate, operating in the weak coupling regime (Fujii et al., 2005). Additionally, methods like Quantum Computed Moments (QCM) address the hardware constraints and noise typical of Near-Term Intermediate Scale Quantum (NISQ) devices, estimating ground state properties even with suboptimal trial states. The strength of this hardware-focused research is its realism regarding current technological limits; however, it often lacks a direct bridge to high-level network protocol verification. Compared to these purely physical studies, our survey integrates physical noise models into a generalized, software-driven protocol verification framework. 4.Approach To systematically evaluate quantum computing security protocols, we propose a structured Quantum Protocol Verification Framework (QPVF). The first module is the "Threat Modeling Engine," which defines the adversary's capabilities, ranging from classical data interception to full quantum memory manipulation. The second module is the "Quantum Circuit Synthesizer," which leverages decision diagram-based tools to translate high-level cryptographic operations into verifiable quantum circuits. The final module is the "Vulnerability Analyzer," which subjects the synthesized circuits to simulated quantum attacks, effectively distinguishing between idealized computational security and realistic hardware-constrained security. This modular pipeline allows security engineers to isolate specific vulnerabilities at both the abstract algorithmic layer and the simulated physical implementation layer. A key design choice in the QPVF is the utilization of decision diagrams for circuit simulation. This choice is predicated on the fact that decision diagrams efficiently handle the exponential state space of quantum systems during complex verification tasks (Wille et al., 2021). Furthermore, our framework explicitly incorporates noise models derived from current NISQ hardware limitations, ensuring that the security evaluation reflects realistic physical constraints rather than purely idealized environments (Vallury & Hollenberg, 2023). To evaluate this framework, we propose a hypothetical benchmarking plan using an artificially generated dataset of 10,000 hybrid quantum-classical cryptographic key exchanges. We will measure the success rate of simulated Grover-based brute-force attacks against varying key sizes and simulated environmental noise levels. This evaluation will compare the theoretical vulnerability threshold of a protocol against the practical threshold observed when quantum noise severely degrades the adversary's computational capabilities. The operational flow of the QPVF is designed to provide end-to-end security verification for next-generation networks. It bridges the critical gap between abstract protocol design and simulated hardware execution. The methodology can be summarized by the following numbered pipeline: Protocol Ingestion: The classical or quantum protocol is parsed into a standardized symbolic representation. Adversary Assignment: The user assigns a precise computational profile, selecting between traditional classical algorithms or advanced quantum capabilities. Circuit Generation: Protocol steps are mapped to equivalent quantum decision diagrams for scalable software simulation. Execution & Attack: Simulated quantum algorithms are executed against the mapped circuits to test for cryptographic resilience. Output Generation: The system outputs a vulnerability score and highlights specific failure points caused by either algorithmic weaknesses or simulated hardware noise. 5.Discussion The transition to quantum-secure protocols carries profound practical implications for global information infrastructure and enterprise deployment. Deploying these advanced protocols requires immense updates to existing software toolkits, as current digital systems are not fundamentally designed to handle the complexity of quantum states. Furthermore, organizations must consider the massive educational and workforce development efforts needed to train software engineers in quantum cryptography, a requirement already highlighted by international hackathons and educational initiatives. Integrating quantum-resistant protocols into complex domains like high-energy physics networks or global banking systems will require bridging the gap between theoretical quantum mechanics and applied computer engineering. Consequently, practical deployment must occur in hybrid phases, maintaining classical cryptographic wrappers while dedicated quantum infrastructure matures. Despite the robust theoretical design of proposed quantum security frameworks, several limitations and failure modes persist in practical applications. First, physical implementation attacks, such as side-channel attacks on the lasers and cavities used in physical quantum gates can bypass theoretical software security guarant
Recent developments in quantum computers pose an imminent threat to cryptography since many widely used cryptographic schemes will no longer be secure. This worrisome scenario motivated a growing interest in the field of post-quantum cryptography, which aims to design cryptosystems that are postquantum secure, i.e. secure against quantum-capable adversaries. While finding post-quantum computational hardness assumptions is pivotal to achieve this goal, an issue that is often overlooked is provable security. In fact, to prove that the post-quantum computational hardness necessarily implies post-quantum security of the derived cryptosystem, the reduction argument that establishes this implication also needs to be post-quantum. As such, many new methods have been devised in the last few years to handle this adaptation to the quantum setting. In particular, the quantum analogue of the Random Oracle Model has garnered special interest, as it is the foundation of many cryptographic schemes, from public-key encryption to digital signatures. It is also very problematic and usually the main culprit of the failure of security proofs when transitioning to the quantum setting. This work offers a comprehensive exposition on the most influential techniques developed in the last decade to enable or facilitate the construction of security proofs in the Quantum Random Oracle Model (QROM). Each presented technique offers an unique purpose and a solution to a problem provoked by the QROM, and, as such, as a whole, this works allows for an understanding of the most common strategies to construct these type of security proofs. This is accomplished by presenting and analyzing the security proof of three cryptographic schemes set in this model, which underlines the central role these techniques take in provable quantum security.
With the rapid advancement regarding quantum computing, traditional cryptographic systems face an existential threat because of their reliance concerning mathematical challenges which may be addressed effectively solved using quantum algorithms like the one developed by Shor. This imminent risk has driven extensive research into quantum-resistant cryptography (PQC), that seeks to develop encryption methods resilient against attacks powered by quantum computing. This study offers a thorough literature survey on high-level security techniques in quantum security for PQC, analysing past and current research efforts in this domain. We first examine the vulnerabilities of classical cryptographic protocols, including public-key encryption methods such as RSA (developed by Rivest, Shamir, and Adleman) and ECC (which uses elliptic curve mathematics), and traditional cryptographic hashing methods, against quantum adversaries. The study then explores the foundational approaches to quantum-secure cryptography, including lattice-based, hash-based, multivariate polynomial, code-based, and isogeny-based encryption methods that possess emerged as promising candidates for standardization. The survey highlights key challenges in the real-world application of PQC, including performance trade-offs, key size overhead, and deployment complexities. We conclude by identifying future research directions during the creation of scalable, efficient, and provably secure cryptographic methods designed to withstand quantum attacks techniques. As the shift toward the quantum-resilient era approaches, this survey aims to provide a clear and structured comprehension of the evolving the domain of quantum security for PQC.