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The ability to control the optical properties of a material with an electric field has led to optical memory devices, communication systems, optical signal processing, or quantum cryptography. Understanding electro-optic effects, especially in thin films, would improve the efficiency of these applications. In particular, the influence of epitaxial strains is of prime importance. In addition, the active control of these effects would be of great interest to tailor the material to the desired performance. Here, we demonstrate through first-principle calculations that the linear electro-optic response (Pockels effect) of two silicon-compatible ferroelectrics is stable with respect to bi-axial strain and that the electro-optic response can be strongly enhanced through the electrical control of the polarization. We attribute the former to the lack of optical phonon softening and a weak elasto-optic response and the latter to the externally induced softening of a phonon of symmetry A 1. Our results are readily applicable to other polar materials and show that the electro-optic effect can be efficiently engineered to meet the performance criteria of future technologies. [ABSTRACT FROM AUTHOR]

The wireless body area network (WBAN) has emerged as a promising networking paradigm thanks to embedded systems, integrated circuit technologies, and wireless communications advancements. WBAN has the ability to send real-time biomedical data to remote medical personnel for clinical diagnostics through intelligent medical sensors in or around the patient's body. Moreover, WBANs have played an increasingly important role in modern medical systems over the past decade as part of the Internet of Things (IoT). In addition to their conveniences, WBANs present us with the data confidentiality challenge and protecting patient's privacy. The system requires a robust security mechanism to protect against threats because of the massive production of delay-sensitive data. This article presents a quantum key distribution (QKD) protocol-based authentication scheme for secure communication within WBAN infrastructure to prevent attacks and provide services free of security risks. To the best of our knowledge, we proposed a privacy preserving quantum authentication scheme for secure data sharing in WBANs to enhance security by encrypting medical data and safeguarding patients identities. Simulations conducted using Mathematica evaluate the proposed quantum authentication protocol both theoretically and practically, showing strong encryption performance against recent schemes. Results include computational cost of 6.832 ms, communication costs of 588 bits, and energy consumption of 432.98 μ J indicating the proposed quantum authentication protocol model exhibits superior reliability, feasibility, and efficiency in safeguarding WBAN data during transmission and storage. [ABSTRACT FROM AUTHOR]

Smart cities, fueled by the Internet of Things (IoT), promise urban efficiency and convenience. However, it has also exposed vulnerabilities in the security and privacy of sensitive data transmitted and stored within these interconnected networks. The increasing frequency of cyberattacks and data breaches underscores the pressing need for innovative solutions to enhance the security of smart city IoT systems. This paper introduces a novel approach to bolstering IoT security in smart cities by adapting quantum cryptography principles. Leveraging quantum steganography, we conceal sensitive data within quantum streams. The proposed model provides a comprehensive solution that ensures the confidentiality, integrity, and authenticity of data within smart city IoT ecosystems. By combining quantum steganography, reversible decoding, customized encryption, privacy amplification, and cryptographic verification, this protocol fosters trust among stakeholders and supports the secure evolution of urban environments. This research offers a blueprint for securing IoT in smart cities, fostering trust, and enabling the safe evolution of urban environments. [ABSTRACT FROM AUTHOR]

With the advent of internet-enabled and hybrid technologies, information is becoming increasingly accessible to the general public. Smartphones and other gadgets are used extensively by people to share and promote ideas, in a variety of ways. Human interaction and communication has become more reliable and effective through advanced computing technologies. Quantum computing is an emerging paradigm that will change the lives of individuals and the operations of organizations. Quantum computers solve problems at high speed by operating in a superposition state in which the state can be either zero or one at the same instant. Quantum sensors can be used efficiently in technological research to make accurate measurements and collect data that provide new insights into the behavior of nanomaterials. The use of quantum computing could also speed up the manufacturing process of devices with remarkable properties such as superconductivity, high strength or improved signal performance. Quantum computing has the ability to dramatically speed up the development process of various organizations and increase their efficiency and effectiveness. The security and reliability of data and communication is improved by quantum computing techniques such as key generation and entanglement dispersion. Companies use cryptographic algorithms to protect their data. However, with the advent of quantum computing, cryptographic methods that rely on numerical aspects are no longer sufficient to protect data. Quantum computing is an emerging field that is being applied to various problems that previously could not be solved using conventional methods. Quantum computing plays an important role in the field of information processing, where information is precisely analyzed. Various quantum technologies and algorithms are used to secure company data. This paper provides a systematic review of the literature on the principles of quantum computing. The SLR focuses on achieving four aims "identifying a variety of quantum IoT devices, analyzing their importance in different industries, highlighting the challenges of quantum technology, and presenting various techniques used by researchers to overcome different problems". Quantum cryptography is identified as a key strategy for improving the security of IoT systems and ensuring the security and consistency of information. [ABSTRACT FROM AUTHOR]

In the era of digital proliferation, individuals opt for cloud servers to store their data due to the diverse advantages they offer. However, entrusting data to cloud servers relinquishes users' control, potentially compromising data confidentiality and integrity. Traditional auditing methods designed to ensure data integrity in cloud servers typically depend on Trusted Third Party Auditors. Yet, many of these existing auditing approaches grapple with intricate certificate management and key escrow issues. Furthermore, the imminent threat of powerful quantum computers poses a risk of swiftly compromising these methods in polynomial time. To overcome these challenges, this paper introduces a Quantum‐based Secure Key Communication and Key Generation Scheme QSKCG for Outsourced Data in the Cloud. Leveraging Elliptic Curve Cryptography, the BB84 secure communication protocol, certificateless signature, and blockchain network, the proposed scheme is demonstrated through security analysis, affirming its robustness and high efficiency. Additionally, performance analysis underscores the practicality of the proposed scheme in achieving post‐quantum security in cloud storage. [ABSTRACT FROM AUTHOR]

Highly efficient and spectrally pure single photon sources are desirable in fundamental studies of quantum physics and in many varied applications like in quantum metrology and quantum cryptography. 2D semiconductor colloidal quantum wells (CQWs) are quite appropriate as nanoscale photon sources because of their giant oscillator strengths and large absorption cross sections. The integration of such sources with dielectric metasurfaces exhibiting narrow resonances provides an excellent platform for highly efficient light‐matter interactions and the development of on‐chip light sources with high spectral purity. Here details on the use of capillary filling method are reported to achieve photonic coupling of CQWs to a metasurface resonator (MSR) featuring a square‐lattice geometry of holes on a slab‐waveguide to achieve strongly enhanced and almost spectrally pure emission of ≈3% of the original out‐of‐plane emission line‐width of the quantum emitters at room temperature. Long‐range exciton‐mediated photon transport facilitated by in‐plane slab waveguide modes is demonstrated and a theoretical basis to explain all the experimental data including that in terms of the MSR‐modified Lamb shifts and Purcell decays is provided. The results demonstrate a new platform with emergent photonic properties and suggest possibility of their use in on‐chip photonic quantum information processing. [ABSTRACT FROM AUTHOR]

Quantum networks that can perform user-defined protocols beyond quantum key distribution will require fully controllable entangled quantum states. To expand the available space of generated time-bin entangled states, we demonstrate a time-bin entangled photon source that produces qubit states | ψ 〉 = α | 00 〉 + β | 11 〉 with fully controllable phase and amplitudes. Eight different two-photon states have been selected and prepared from arbitrary states on the reduced two-qubit Bloch sphere. The photon pairs encoded in the time-bin scheme were generated at 2.4 MHz with a visibility of V = 0.9475 ± 0.0016 , with a violation of the CHSH Bell's inequality by 197 standard deviations. After entanglement distribution over 100 km of single-mode fibers, we obtained a visibility of V = 0.9541 ± 0.0113 with a violation of the CHSH Bell's inequality by 6 standard deviations. The prepared states had an average fidelity of 0.9540 ± 0.0016 at the source and an average fidelity of 0.9353 − 0.0209 + 0.0100 after entanglement distribution, which shows that the quantum states generated by our time-bin entangled photon source can be fully controlled potentially to a level applicable to long-distance advanced quantum network systems. [ABSTRACT FROM AUTHOR]

Digital signatures are one of the key cryptographic components for providing authenticity and non-repudiation. To circumvent the need of certificates, Shamir in 1984 introduced identity-based signature (IBS). Nearly all of the existing state-of-the-art IBS schemes are relying on the number-theoretic hardness assumptions. Unfortunately, these hard problems are insecure and face a threat in quantum world. Thus, it is high time to design and analyze IBS algorithms that can resist quantum attacks and provide long-term security. Quantum cryptography is one such technique to provide quantum-safe IBS. In this paper, we cryptanalyze the quantum cryptography-based IBS of Huang et al. (Huang et al. in Quantum Inf Process 22(1):36, 2022). We show that the design in (Huang et al. in Quantum Inf Process 22(1):36, 2022) is not secure against public key generator forgery attack, collusion attacks, and intercept and resend attacks. Next, we modify the design of (Huang et al. in Quantum Inf Process 22(1):36, 2022) and propose a new quantum IBS (namely qIBS) which is secure against the aforementioned attacks. [ABSTRACT FROM AUTHOR]

Quantum random number generation (QRNG) leveraging intrinsic quantum uncertainty has attracted significant interest in the field of integrated photonic architecture, with applications in quantum cryptography, tests of quantum nonlocality, and beyond. The demand for compact, low-energy consumption, robust, fast, and cost-effective QRNGs integrated into photonic chips is highlighted, whereas most previous works focused on bulk optics. Here, based on the metalens array entangled source, we experimentally realized a miniaturized, high-dimensional quantum random number generator via a meta-device without post-randomness extraction. Specifically, the device has a high-density output with 100 channels per square millimeter. This chip-scale quantum randomness source can obtain random number arrays without post-randomness extraction and enable compact integration for quantum applications needing secure keys or randomness. Our approach demonstrates potential in secure key generation and randomness for quantum applications. [ABSTRACT FROM AUTHOR]

Modern technologies like quantum and cloud computing have reshaped computing, offering immense power and scalability. While beneficial, they also challenge the security of traditional cryptographic systems. Quantum computing threatens RSA and ECC with algorithms like Shor's algorithm, which can accelerate computations exponentially. This risks exposing these systems to attacks, necessitating quantum-resistant cryptography. Cloud computing poses data security concerns, requiring robust cryptographic mechanisms and access controls. Lattice-based cryptography, leveraging problems like the Short Integer Solution (SIS), emerges as a solution. This paper presents a novel quantum-resistant public key encryption scheme based on ElGamal and SIS, ensuring security against quantum and classical threats in modern cryptographic environments. [ABSTRACT FROM AUTHOR]

In this work, we present a new protocol that accomplishes multiparty quantum private comparison leveraging maximally entangled | G H Z 3 〉 triplets. Our intention was to develop a protocol that can be readily executed by contemporary quantum computers. This is possible because the protocol uses only | G H Z 3 〉 triplets, irrespective of the number n of millionaires. Although it is feasible to prepare multiparticle entangled states of high complexity, this is overly demanding on a contemporary quantum apparatus, especially in situations involving multiple entities. By relying exclusively on | G H Z 3 〉 states, we avoid these drawbacks and take a decisive step toward the practical implementation of the protocol. An important quantitative characteristic of the protocol is that the required quantum resources are linear both in the number of millionaires and the amount of information to be compared. Additionally, our protocol is suitable for both parallel and sequential execution. Ideally, its execution is envisioned to take place in parallel. Nonetheless, it is also possible to be implemented sequentially if the quantum resources are insufficient. Notably, our protocol involves two third parties, as opposed to a single third party in the majority of similar protocols. Trent, commonly featured in previous multiparty protocols, is now accompanied by Sophia. This dual setup allows for the simultaneous processing of all n millionaires' fortunes. The new protocol does not rely on a quantum signature scheme or pre-shared keys, reducing complexity and cost. Implementation wise, uniformity is ensured as all millionaires use similar private circuits composed of Hadamard and CNOT gates. Lastly, the protocol is information-theoretically secure, preventing outside parties from learning about fortunes or inside players from knowing each other's secret numbers. [ABSTRACT FROM AUTHOR]

The Quantum Key Distribution (QKD) network approach has emerged as a promising solution and has garnered significant interest across various domains. QKD networks can be broadly categorized into two main types: those based on measurement-device-dependent (MDD) protocols and those based on measurement-device-independent (MDI) protocols. A novel network scheme is proposed combining these two protocols to guarantee end-to-end secure communication. It comprises two interconnected networks — the first uses a measurement-device-dependent protocol to connect routers with nearby nodes, while the second employs a measurement-device-independent protocol to interconnect the routers. In the first network, the process begins with Alice (Router) generating two types of weak quantum signals — the first has intensity, frequency and polarization or phase randomly varied, while the second with different delay times. Alice randomly transmits either signal states carrying information or decoy states with varying properties to the receivers (Bobs) over the quantum channels. She also sends a synchronization signal along with the quantum signals. At the receiver end, the synchronization pulse timestamps the incoming quantum signals. Each Bob then randomly shifts the frequencies of the received signals and measures their phase/polarization of the first signal and measures the delay times of the second signal. The secret key is derived by combining the frequency, the delay time and the phase/polarization information of the quantum signals, resulting in longer key lengths. Encoding information across multiple degrees of freedom enables extended key generation for secure communication. However, between the routers, MDI-QKD protocols are used to securely share the keys. This hybrid approach aims to ensure secure end-to-end communication across the network. [ABSTRACT FROM AUTHOR]

Quantum computing provides a revolution in computational competences, leveraging the principles of quantum mechanics to process data in fundamentally novel ways. This paper explores the profound implications of quantum computing on cryptography, focusing on the vulnerabilities it introduces to classical encryption methods such as RSA and ECC, and the emergence of quantum-resistant algorithms. We review the core principles of quantum mechanics, including superposition and entanglement, which underpin quantum computing and cryptography. Additionally, we examine quantum encryption algorithms, particularly Quantum Key Distribution (QKD) protocols and post-quantum cryptographic methods, highlighting their potential to secure communications in the quantum era. This analysis emphasizes the urgent need for developing robust quantum-resistant cryptographic solutions to safeguard sensitive information against the imminent threats posed by advancing quantum technologies. [ABSTRACT FROM AUTHOR]

In recent research, there has been a significant focus on establishing robust quantum cryptography using the continuous-variable quantum key distribution (CV-QKD) protocol based on Gaussian modulation of coherent states (GMCS). Unlike more stable fiber channels, one challenge faced in free-space quantum channels is the complex transmittance characterized by varying atmospheric turbulence. This complexity poses difficulties in achieving high transmission rates and long-distance communication. In this article, we thoroughly evaluate the performance of the CV-QKD/GMCS system under the effect of individual attacks, considering homodyne detection with both direct and reverse reconciliation techniques. To address the issue of limited detector efficiency, we incorporate the phase-sensitive amplifier (PSA) as a compensating measure. The results show that the CV-QKD/GMCS system with PSA achieves a longer secure distance and a higher key rate compared to the system without PSA, considering both direct and reverse reconciliation algorithms. With an amplifier gain of 10, the reverse reconciliation algorithm achieves a secure distance of 5 km with a secret key rate of 10 − 1 bits/pulse. On the other hand, direct reconciliation reaches a secure distance of 2.82 km. [ABSTRACT FROM AUTHOR]

The discrete-logarithm problem and related problems are important in public-key cryptography; however, these problems can be reduced to the hidden-subgroup problem (HSP) of an abelian group, for which efficient quantum algorithms exist. This paper more broadly regards these problems as semigroup-action problems (SAPs) on different modules. The results prove that if the action on a module is injective or the cardinality of the hidden subgroup's least generating set is less than or equal to that of the ring's least generating set, the corresponding SAP on the module can be reduced to the HSP of an abelian group in polynomial time; therefore, most cryptosystems based on the SAP on a module cannot resist quantum cryptanalysis. The results are applicable to the discrete-logarithm problem and matrix-action problem on a group, along with other SAPs on a module. Such reduction is not be found for the SAP on the semi-module. The cryptographic systems based on SAPs on some semi-modules are likely to resist quantum attacks. [ABSTRACT FROM AUTHOR]

With the rapid development of quantum computing technology, the traditional cryptosystem will face a significant threat. It is an urgent security issue to study the security impact of quantum computing on classical cryptosystems and provide reliable cryptographic primitives for the post-quantum era. A powerful way to solve this problem is to quantize the classical cryptanalysis tools and use the improved versions for cryptanalysis. In this paper, we propose a quantum Zero-correlation analysis algorithm based on the Bernstein–Vazirani and Grover algorithms. It can find zero-correlation linear hulls for Feistel and SPN structures. We prove the correctness of the algorithm and analyze its complexity. Compared with the classical algorithms, the proposed quantum algorithm has significant advantages when the number of encryption rounds of block ciphers is large. Moreover, compared with the existing quantum Zero-correlation linear analysis, the proposed algorithm is more efficient and does not depend on the algebraic characteristics of the target cipher, which makes the algorithm has more flexible application scenarios. With the development of quantum computers, we discuss the threat of quantum cryptanalysis algorithms to classical security. [ABSTRACT FROM AUTHOR]

The current blockchain systems lack the ability to resist quantum computing attacks. This puts the confidentiality and integrity of data in blockchain-based data sharing at risk. The security of data sharing faces the new challenges. In this paper, a blockchain data sharing scheme based on quantum re-encryption is proposed. The presented scheme uses quantum key and unitary matrix to encrypt data for two times. It ensures data sharing between the data owner and the data accessor without revealing the owner's private key. Moreover, it utilizes a quantum hash function based on controlled alternate quantum walks to compute quantum hash value. The obtained hash value has higher randomness, collision resistance and input sensitivity. Additionally, this method combines on-chain and off-chain storage. The combined storage method effectively alleviates the storage pressure on the blockchain. Finally, the security of the proposed scheme is analyzed. The results show that this scheme ensures the integrity, confidentiality and non-tampering of the shared data. At the same time, it protects the security of data owner's private keys. [ABSTRACT FROM AUTHOR]

In this paper, the authors present a technique for developing a secure messaging service called "CryptoMess" which utilizes the Commutative Supersingular Isogeny Diffie-Hellman (CSIDH) algorithm for secure key exchange and the Advanced Encryption Standard (AES) to protect message content in communication. In addition, the authors have incorporated the Falcon post-quantum digital signature technology to ensure the integrity and authenticity of communications between the sender and the recipient. The novel post-quantum cryptographic algorithms utilized by the authors are still under consideration in the competition to select cryptosystems for use in quantum computing systems organized by the NIST Standards Institute. As a result, the messaging program "CryptoMess" is able to exchange messages between users, providing safety, security, integrity, and authenticity. The authors have included modern post-quantum cryptography techniques, such as the Falcon digital signature system, to guarantee that the product operates safely. The program has a transmitting rate of approximately 209–261 ms and a receiving rate of approximately 168–206 ms. The message signing time is about 260 ms, and the message verification speed is approximately 185 ms. Key generation time is about 741 ms, key encapsulation time is about 1.454 ms, and key decapsulation time is about 1.921 ms. The source code of the "CryptoMess" communications program has been analyzed and tested by the authors using the Fortify Static Code Analyzer tool to ensure that the product has been created safely and securely. [ABSTRACT FROM AUTHOR]

This study develops a technology analysis to detect technological trajectories in quantum computing that can lay the foundation of a quantum industry. Study design considers data of 10,089 scientific products in 'quantum computing' over 1989–2020 period and 19,266 scientific products in 'quantum computer' over 1967–2020 period to cover all scientific production in this research field; a complementary analysis considers 8,505 patents over 1977–2020 in 'quantum computing' and 9,792 patents in 'quantum computer' over 1985–2020 period. Models of technological evolution applied here show main technological trajectories in quantum computing and computer and their rates of growth that suggest path-breaking directions in quantum technology, such as quantum optics, quantum information, quantum algorithms, quantum entanglement, quantum communication and quantum cryptography. Findings here provide information to extend the knowledge in the evolution of quantum computing and computers to support the management of these new technologies and R&D investments towards innovations generating industrial, economic and social change. [ABSTRACT FROM AUTHOR]

It is well known that many of the traditional cryptographic schemes (like RSA and DH) will be vulnerable when scalable quantum computers will be available. However, quantum cryptographic protocols can provide unconditional security. One such protocol for quantum key distribution (QKD) is coherent one way (COW) protocol which is realized often because of ease of implementation, though the security proof is still an open problem. In the present work, we report experimental realization of an optical fiber based COW protocol for QKD in the telecom wavelength (1550 nm) where the attenuation in the optical fiber is minimum. A laser of 1550 nm wavelength, attenuator and intensity modulator is used for the generation of pulses having average photon number 0.5 and repetition rate of 500 MHz. The experiment is performed over 40, 80 and 120 km of optical fiber and several experimental parameters like disclose rate, compression ratio, dead time and excess bias voltage of the detector are varied for all the cases (i.e., for 40, 80 and 120 km distances) to observe their impact on the final key rate. Specifically, it is observed that there is a linear increase in the key rate as we decrease compression ratio or disclose rate. The key rate obtains its maximum value for least permitted values of disclose rate, compression ratio and dead time. It seems to remain stable for various values of excess bias voltage. While changing various parameters, we have maintained the quantum bit error rate (QBER) below 6% (5%) for distance ≥ 120 km ( ≤ 120 km). The key rate obtained is also found to remain stable over time. Experimental results obtained here are also compared with the earlier realizations of the COW QKD protocol. Further, to emulate key rate at intermediate distances and at a distance larger than 120 km, an attenuator of 5 dB loss is used which can be treated as equivalent to ∼ 25 km of the optical fiber used in the present implementation. This has made the present implementation equivalent to the realization of COW QKD upto ∼ 145 km. [ABSTRACT FROM AUTHOR]

Quantum private comparison (QPC) represents a cryptographic approach that enables two parties to determine whether their confidential data are equivalent, without disclosing the actual values. Most existing QPC protocols utilizing single photons or Bell states are considered highly feasible, but they suffer from inefficiency. To address this issue, we present a novel QPC protocol that capitalizes on the entanglement property of Bell states and local operations to meet the requirements of efficiency. In the proposed protocol, two participants with private inputs perform local operations on shared Bell states received from a semi-honest third party (STP). Afterward, the modified qubits are returned to the STP, who can then determine the equality of the private inputs and relay the results to the participants. A simulation on the IBM Quantum Cloud Platform confirmed the feasibility of our protocol, and a security analysis further demonstrated that the STP and both participants were unable to learn anything about the individual private inputs. In comparison to other QPC protocols, our proposed solution offers superior performance in terms of efficiency. [ABSTRACT FROM AUTHOR]

To address the potential threat to the power grid industry posed by quantum computers and ensure the security of bidirectional communication in smart grids, it is imperative to develop quantum-safe authentication protocols. This paper proposes a semi-quantum bidirectional authentication protocol between a control center (CC) and a neighboring gateway (NG). This method uses single photons to facilitate communication between the CC and the NG. Security analysis demonstrates that the protocol can effectively resist common attack methods, including double CNOT attacks, impersonation attacks, interception-measurement-retransmission attacks, and entanglement-measurement attacks. Comparisons with other protocols reveal that this protocol has significant advantages, making it more appealing and practical for real-world applications. Finally, by simulating the protocol on the IBM quantum simulator, this protocol not only validates the theoretical framework but also confirms the practical feasibility of the protocol. [ABSTRACT FROM AUTHOR]

This paper introduced a novel semiring structure involving nonnegative integers, where operations depended on the comparison of the magnitudes of decimal digit sums. Consequently, a corresponding matrix semiring can be established on this commutative semiring. We showed that the 3-satisfiability problem can be polynomial-time reduced to solving systems of quadratic polynomial equations over this semiring. We proposed a key exchange protocol based on this matrix semiring, with its security relying on the two-sided digital circulant matrix action problem over this semiring. This scheme provides a novel cryptographic primitive for post-quantum cryptography. [ABSTRACT FROM AUTHOR]

This paper simulated the operation of vacuum state and single decoy state protocols in the BB84 and SARG04 QKD schemes by utilizing the features of the commercial ID-3000 QKD system. Numerical modeling identified an optimal signal-to-decoy state ratio of 0.95:0.05 and an intensity of μ=0.85 for the signal state and ν1=0.05 for the decoy state, ensuring the highest key generation rate and a secure distance of up to 50 km. These protocols were validated experimentally over various transmission distances with standard telecom fiber, using the ID-3000 QKD system in a conventional bi-directional plug-and-play setup. Simulations predicted secure key rates of 1.2 × 105 bits/s for SARG04 and 8.5 × 104 bits/s for BB84 at 10 km, with secure distances of 45 km and 35 km, respectively. The experimental results confirmed these predictions, showing a 30% higher key rate and 20% longer secure distance compared to non-decoy methods. The SARG04 protocol surpassed BB84 in key rate and secure distance, highlighting the twophoton component's role in key generation. This study concludes that the decoy-state method significantly enhances key generation rates and secure distances, optimizing QKD protocols for secure quantum communication. [ABSTRACT FROM AUTHOR]

Shor's factorization algorithm (SFA) aims at finding the non-trivial factor of a given composite number, but the algorithm does not always work. In some cases, it has to call back to the beginning of the algorithm to make recalculation. After the analysis of the principle of SFA and the characteristics of RSA public-key cryptography with a series of data calculations, it can be concluded that the random value selected by the algorithm is closely related to whether the obtained period is effective. Therefore, a new optimized scheme is proposed to tackle with this defect from two perspectives: (a) When the a value is a perfect square, the algorithm can be completed with an odd cycle r. (b) When the period r obtained by the randomly selected a value is a multiple of 3 , the algorithm can be completed by modifying the decomposition method to relax the requirements for the period without affecting the complexity of the algorithm. Due to the limitations of hardware in applying the quantum algorithms, the classical algorithm is applied to simulate quantum algorithms to test the success rate of decomposition of some composite numbers. The result indicates the effectiveness of the improved algorithm, which significantly reduces the probability of repeated operations to save the quantum circuit resources. [ABSTRACT FROM AUTHOR]

Oblivious transfer (OT) is a significant two party privacy preserving cryptographic primitive. OT involves a sender having several pieces of information and a receiver having a choice bit. The choice bit represents the piece of information that the receiver wants to obtain as an output of OT. At the end of the protocol, sender remains oblivious about the choice bit and receiver remains oblivious to the contents of the information that were not chosen. It has applications ranging from secure multi-party computation, privacy-preserving protocols to cryptographic protocols for secure communication. Most of the classical OT protocols are based on number theoretic assumptions which are not quantum secure and existing quantum OT protocols are not so efficient and practical. Herein, we present the design and analysis of a simple yet efficient quantum OT protocol, namely qOT. qOT is designed by using the asymmetric key distribution proposed by Gao et al. (Opt Express 20(16):17411–17420, 2012) as a building block. The designed qOT requires only single photons as a source of a quantum state, and the measurements of the states are computed using single particle projective measurement. These make qOT efficient and practical. Our proposed design is secure against quantum attacks. Moreover, qOT also provides long-term security. [ABSTRACT FROM AUTHOR]

Conventional signcryption schemes that depend on discrete logarithm problem, big integer prime factorization, and bilinear pairing are at risk in the context of quantum computers. We suggest a signcryption scheme based on a lattice to overcome the problems posed due to potential quantum computers in healthcare management which is named as lattice-based ring signcryption scheme for smart healthcare management (LRS-SHM). Unlike existing schemes, our design uses regenerated keys for every signature generated by user itself (instead of a key generation center), thus protecting the privacy of the user. Furthermore, we provide an anonymous health record management scheme that combines a (t, n) threshold method with our lattice-based signcryption system in an effort to overcome the existing anonymity limits in health record administration, especially in light of quantum computing concerns. We show the anonymity of our lattice-based signcryption method against confidentiality and its existential non-forgeability against insider corruption in the context of health record administration, proving security under the random oracle model. We compare our proposed scheme with existing schemes and found that our scheme is more efficient than others. By the use of (t, n) threshold scheme, we protect our scheme from single point of failure because we distribute the secret share to n number of users and to reconstruct the secret the scheme requires at least t users. Empowering privacy, our lattice-based signcryption prevents quantum threats, introduces seamless key control, and enhances health record anonymity, setting a new standard for secure and efficient cryptographic solutions. [ABSTRACT FROM AUTHOR]

In the last couple of decades, Attribute-Based Encryption (ABE) has been a promising encryption technique to realize fine-grained access control over encrypted data. ABE has appealing functionalities such as (i) access control through encryption and (ii) encrypting a message to a group of recipients without knowing their actual identities. However, the existing state-of-the-art ABEs are based on number-theoretic hardness assumptions. These designs are not secure against attacks by quantum algorithms such as Shor algorithm. Moreover, existing Post-Quantum Cryptography (PQC)-based ABEs fail to provide long-term security. Therefore, there is a need for quantum secure ABE that can withstand quantum attacks and provides long-term security. In this work, for the first time, we introduce the notion of a quantum-secure ABE (qABE) framework that preserves the classical ABE's functionalities and resists quantum attacks. Next, we provide a generic construction of qABE which is able to transform any existing ABE into qABE scheme. Thereafter, we illustrate a concrete construction of a quantum ABE based on our generic transformation qABE and the Waters' ciphertext-policy ABE scheme. [ABSTRACT FROM AUTHOR]

Quantum identity authentication is one of the important branches of quantum cryptography. By means of the advantages of measurement-device-independent technique, in this paper, we propose a new two-party quantum identity authentication protocol, which is further extended to the multiparty quantum identity authentication protocol. It naturally removes the side-channel attacks caused by the detector loophole. Compared with the multi-party simultaneous quantum authentication protocols based on GHZ states, the proposed protocol may be more suitable for long-distance and large-scale multi-party authentication. [ABSTRACT FROM AUTHOR]

Quantum secure direct communication (QSDC) can directly transmit secret messages through quantum channel without keys. Device-independent (DI) QSDC guarantees the message security relying only on the observation of the Bell-inequality violation, but not on any detailed description or trust of the devices’ inner workings. Compared with conventional QSDC, DI-QSDC has relatively low secret message capacity. To increase DI-QSDC’s secret messages capacity, we propose a high-capacity DI-QSDC protocol based on the hyper-encoding technique. The total message leakage rate of our DI-QSDC protocol only relies on the most robust degree of freedom. We provide the numerical simulation of its secret message capacity altered with the communication distance. Our work serves as an important step toward the further development of DI-QSDC systems.

The field of computing is about to undergo a revolution thanks to quantum computing, a ground-breaking innovation based on the ideas of quantum physics. The enormous implications and potential that quantum computing has for cloud computing are explored in this publication. We examine the difficulties faced by current cryptography systems as well as prospective improvements in fields like machine learning, simulations, and data security as we delve into the basic alterations in computing paradigms. Additionally, we go over the revolutionary possibilities for cloud computing, such as the creation of quantum-safe cloud security solutions, hybrid computing models, and quantum cloud services.

Abstract The quantum communication channel is considered to be eavesdropped when the signal Quantum Bit Error Rate (QBER) exceeds a defined theoretical limit and is thus considered a figure of merit parameter for assessing the security of a quantum channel. This work presents a general mathematical model considering device imperfections and various sources of errors for estimating signal QBER in polarisation encoded satellite‐based QKD systems. QBER performance for satellite‐to‐ground downlink scenarios has been investigated for multiple sky brightness conditions (day time and night time operations), two operating wavebands: 800 and 1550 nm as well as for different quantum transmitter and quantum receiver architectures. Further, a novel QBER estimation analysis for inter‐satellite QKD links has also been presented. The estimation results obtained from the developed model have been validated against and found in good agreement with the measured results of the only reported satellite‐to‐ground QKD experiments till date. The presented QBER modelling and analysis will aid in system engineering and efficient design of future satellite‐based QKD systems.

Password-based authentication is one of the most prevailing access control mechanism. Typical password-authenticated key exchange (PAKE) protocols are single-server settings and are therefore vulnerable to server compromise attack. To defend against such attack, multi-server PAKE schemes have been advanced, but most of which are built on non-quantum-secure hardness assumptions. Lattice-based cryptosystems are regarded as the most promising one for post-quantum eara by NIST, while the known multi-server password-based authentication solution over lattices achieves merely key transport and is public key infrastructure (PKI)-based, resulting in low efficiency and poor deployability. In this work, we resort to distributed smooth projective hash function (SPHF) to bridge the gap between multi-server PAKE protocol and quantum-security. We first design an exact SPHF and derive the first distributed SPHF over lattices by leveraging the additive homomorphic property of the strong learning with errors (LWE) problem. In particular, the relevant parameters of the public key encryption (PKE) scheme it predicates on are identified, thus eliminating the influence of incomplete lattice homomorphism on the correctness of our SPHFs. Pertinent lattice-based multi-server PAKE protocols are further proposed on both transparent and non-transparent transmission modes by integrating our distributed SPHF into the multi-server framework of Raimondo and Gennaro (EUROCRYPT'03). Our PAKE constructions are able to resist both quantum and sever compromise attacks as well as avoid the expensive cryptographic primitives, including non-interactive zero knowledge (NIZK) proofs, signature/verification, secret sharing and fully homomorphic encryption. Experimental results demonstrate that our SPHFs and PAKE protocols offer better efficiency. [ABSTRACT FROM AUTHOR]

Hermite–Korkin–Zolotarev (HKZ) reduction is an important notion of lattice reduction which plays a significant role in number theory (particularly the geometry of numbers), and more recently in coding theory and post-quantum cryptography. In this work, we determine a sharp upper bound on the orthogonality defect of HKZ reduced bases up to dimension 3. Using this result, we determine a general upper bound for the orthogonality defect of HKZ reduced bases of arbitrary rank. This upper bound is sharper than existing bounds in literature, such as the one determined by Lagarias, Lenstra and Schnorr [3]. [ABSTRACT FROM AUTHOR]

A significant topic of contemporary cryptography research and standardization is the development of public key crypto systems that resist attacks from quantum computers. Protocols and applications should start investigating the use of quantumresistant key exchange and encryption to protect the confidentiality of current communications against future quantum computers utilizing post-quantum cryptography for a particular key exchange. Since they operate harder and need fewer steps compared to conventional computers, quantum algorithms are more secure and robust. Attackers who use quantum computers have powerful computing capabilities, and a quantum allows for simple cryptographic system breaking. Security algorithms that are quantum secure are resistant to attacks from conventional, as well as quantum computers. This work has surveyed, summarized, and analysed previous research to provide readers of this study an integrated understanding of quantum cryptography. It also discusses quantum attacks, which could be used in place of more conventional cryptography techniques, such as quantum key distribution, which takes advantage of quantum mechanics' properties to ensure secure exchanges of the secret keys, and various quantum algorithms. With quantum computation becoming a very real threat, this should motivate more people to show an early interest in the future of cryptography. [ABSTRACT FROM AUTHOR]

It is known that the Frenet–Serret apparatus of a space curve in three-dimensional Euclidean space determines the local geometry of curves. In particular, the Frenet–Serret apparatus specifies important geometric invariants, including the curvature and the torsion of a curve. It is also acknowledged in quantum information science that low complexity and high efficiency are essential features to achieve when cleverly manipulating quantum states that encode quantum information about a physical system. In this paper, we propose a geometric perspective on how to quantify the bending and the twisting of quantum curves traced by dynamically evolving state vectors. Specifically, we propose a quantum version of the Frenet–Serret apparatus for a quantum trajectory in projective Hilbert space traced by a parallel-transported pure quantum state evolving unitarily under a stationary Hamiltonian specifying the Schrödinger equation. Our proposed constant curvature coefficient is given by the magnitude squared of the covariant derivative of the tangent vector | T 〉 to the state vector | Ψ 〉 and represents a useful measure of the bending of the quantum curve. Our proposed constant torsion coefficient, instead, is defined in terms of the magnitude squared of the projection of the covariant derivative of the tangent vector | T 〉 , orthogonal to both | T 〉 and | Ψ 〉. The torsion coefficient provides a convenient measure of the twisting of the quantum curve. Remarkably, we show that our proposed curvature and torsion coefficients coincide with those existing in the literature, although introduced in a completely different manner. Interestingly, not only we establish that zero curvature corresponds to unit geodesic efficiency during the quantum transportation in projective Hilbert space, but we also find that the concepts of curvature and torsion help enlighten the statistical structure of quantum theory. Indeed, while the former concept can be essentially defined in terms of the concept of kurtosis, the positivity of the latter can be regarded as a restatement of the well-known Pearson inequality that involves both the concepts of kurtosis and skewness in mathematical statistics. Finally, not only do we present illustrative examples with nonzero curvature for single-qubit time-independent Hamiltonian evolutions for which it is impossible to generate torsion, but we also discuss physical applications extended to two-qubit stationary Hamiltonians that generate curves with both nonzero curvature and nonvanishing torsion traced by quantum states with different degrees of entanglement, ranging from separable states to maximally entangled Bell states. In the Appendix C, we examine the different curvature and torsion characteristics of the three qubit | GHZ 〉 and | W 〉 states under evolution by a quantum Heisenberg Hamiltonian. [ABSTRACT FROM AUTHOR]

In this paper, a new hybrid chaotic-quantum encryption model is investigated aiming to solve the interception trouble of information transmission through insecure environment. In this model, the image encryption method is studied using block diagonal chaotic (BDC) matrix and quantum based private key. The block diagonal chaotic model is designed with structured matrix based on two different nonlinear chaotic sequences and private key bits combined with quantum walks (QWs) path. At sender, the key bits convert to QWs states to increase tamper resistant of quantum key distribution in noisy communication channel. At the receiver side, the received data is retrieved merely by both initial key bits and states as similar as the sender initial key bits and states. If the eavesdropper attempts to measure quantum based private key, the key bits change to different states compared to real sender states and drops the bits eavesdropped in quantum channel. We call the hybrid chaotic image encryption method with private key based on quantum states as chaotic quantum key distribution (CQKD) method. The key space is evaluated using CQKD model rather than chaotic based encryption method without quantum distributed states over impure channels. Considering the sensitivity of block diagonal chaotic-based encryption BDC method with accuracy of 10(−32), the key space is increased from 10 111 to 10 142 × 10 a × f (Δ Φ) × (1 Δ p e ) N e with phase-shifted QWs. It guarantees no information access by attackers considering high security against brute-force attacks and outperforms rather than the conventional chaotic encryption schemes. [ABSTRACT FROM AUTHOR]

In the modern era of the Internet of Things (IoT), especially with the rapid development of quantum computers, the implementation of postquantum cryptography algorithms in numerous terminals allows them to defend against potential future quantum attack threats. Lattice-based cryptography can withstand quantum computing attacks, making it a viable substitute for the currently prevalent classical public-key cryptography technique. However, the algorithm's significant time complexity places a substantial computational burden on the already resource-limited chip in the IoT terminal. In lattice-based cryptography algorithms, the polynomial multiplication on the finite field is well known as the most time-consuming process. Therefore, investigations into efficient methods for calculating polynomial multiplication are essential for adopting these quantum-resistant lattice-based algorithms on a low-profile IoT terminal. Number theoretic transform (NTT), a variant of fast Fourier transform (FFT), is a technique widely employed to accelerate polynomial multiplication on the finite field to achieve a subquadratic time complexity. This study presents an efficient FPGA-based implementation of number theoretic transform for the CRYSTAL Kyber, a lattice-based public-key cryptography algorithm. Our hybrid design, which supports both forward and inverse NTT, is able run at high frequencies up to 417 MHz on a low-profile Artix7-XC7A100T and achieve a low latency of 1.10 μ s while achieving state-of-the-art hardware efficiency, consuming only 541-LUTs, 680 FFs, and four 18 Kb BRAMs. This is made possible thanks to the newly proposed multilevel pipeline butterfly unit architecture in combination with employing an effective coefficient accessing pattern. [ABSTRACT FROM AUTHOR]

Recently, an appreciable number of protocols for quantum key distribution (QKD) have been experimentally realized as they are expected to be unconditionally secure. Among these QKD protocols, two protocols of distributed phase reference type [namely, coherent one way (COW) and differential phase shift (DPS) QKD protocols] have undergone rapid experimental developments due to the ease of implementation with the presently available technology. In this work, we have experimentally realized optical fibre based COW and DPS protocols for QKD where weak coherent pulses are used to encode the information. Further, we have analysed the key rates with respect to different parameters such as distance, disclose rate, compression ratio and detector dead time. [ABSTRACT FROM AUTHOR]

Nowadays, pairing-based cryptography researchers are looking for new parameters for standard security levels against the new number field sieve tower number field sieve algorithm. Recently, they have suggested new parameters for well-studied pairing-friendly curves with odd embedding degrees five and seven resistant to this attack. In this paper, we define optimal ate pairing on curves using sparse families with embedding degrees five and seven. We also provide details to perform the miller loop and the final exponentiation using addition chain process. Our theoretical results costs indicate that these families of curves offer the best performance in the computation of the optimal ate pairing at the 128-bit security level compared to Cocks–Pinch curves of embedding degrees five and seven. The improvement is about 8 , 8 % and 1 9 % faster than the optimal ate pairing previously computed on Cocks–Pinch curves of embedding degrees five and seven, respectively. [ABSTRACT FROM AUTHOR]

Isogeny-based cryptography holds significant promise in the realm of post-quantum cryptography, primarily due to its perceived resilience against attacks from quantum computers, based on our current understanding of the underlying mathematical problems. However, it's essential to acknowledge the dynamic nature of post-quantum cryptography, where ongoing research may yield profound insights or lead to the development of novel cryptographic approaches. This study delves into the analysis of Hessian form curves within the framework of isogeny-based cryptography (IBC). We specifically investigate the computational costs associated with deriving Hessian form curves for constructing sections, particularly when employing compression functions. The square-root Velu method is utilized for handling Hessian form curves, and we introduce a novel formula for calculating the curve's coefficient at a specific point on a Hessian curve. Our results indicate that the operational costs of the Hessian form and the Montgomery curve are comparable. Furthermore, we propose the Hessian-Edwards hybrid model, optimizing Hessian-CSIDH and determining the coefficient for the codomain's curve using Edwards curves. According to our findings, various Isogeny-based cryptosystems can be implemented by leveraging Hessian curves. [ABSTRACT FROM AUTHOR]

The socialist millionaire problem aims to compare the equality of two inputs from two users while keeping their inputs undisclosed to anyone. Quantum private comparison (QPC), whose security relies on the principles of quantum mechanics, can solve this problem and achieve the information-theoretic security of information processing. The current QPC protocols mainly utilize the bitwise XOR operation to implement the comparison, leading to insufficient security. In this paper, we propose a rotation operation-based QPC protocol to solve the socialist millionaire problem, which utilizes Bell states as quantum resources and rotation operations for classical calculations. The proposed protocol only utilizes easy-to-implement technologies such as Bell states, rotation operations, and Bell-basis measurements, making it more practical. The analysis demonstrates that our protocol can meet both the correctness and security requirements. Compared with the existing QPC protocols, our protocol has improved performance in terms of practicability and security. [ABSTRACT FROM AUTHOR]

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