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We show the following hold, unconditionally unless otherwise stated, relative to a random oracle: — There are NP search problems solvable by quantum polynomial-time (QPT) machines but not classical probabilistic polynomial-time (PPT) machines. — There exist functions that are one-way, and even collision resistant, against classical adversaries but are easily inverted quantumly. Similar counterexamples exist for digital signatures and CPA-secure public key encryption (the latter requiring the assumption of a classically CPA-secure encryption scheme). Interestingly, the counterexample does not necessarily extend to the case of other cryptographic objects such as PRGs. — There are unconditional publicly verifiable proofs of quantumness with the minimal rounds of interaction: for uniform adversaries, the proofs are non-interactive, whereas for non-uniform adversaries the proofs are two message public coin. — Our results do not appear to contradict the Aaronson-Ambanis conjecture. Assuming this conjecture, there exist publicly verifiable certifiable randomness, again with the minimal rounds of interaction. By replacing the random oracle with a concrete cryptographic hash function such as SHA2, we obtain plausible Minicrypt instantiations of the above results. Previous analogous results all required substantial structure, either in terms of highly structured oracles and/or algebraic assumptions in Cryptomania and beyond. [ABSTRACT FROM AUTHOR]

The dual-scrambling scheme that combines position transformation and bit-plane transformation is a popular image encryption scheme. However, such schemes need more key information, and the encryption and decryption processes are complicated. In addition, the existing quantum image dual-scrambling schemes mainly deal with square images. In this paper, we propose a hybrid scrambling encryption scheme for multi-mode quantum image representation (MQIR) images based on random permutation, in which the H × W quantum image is represented in MQIR. A random number generator factor s uniquely associates one of the random permutations of integers from 1 to a positive integer, so as to hybrid scramble both the pixel position and the binarized position of each pixel value. Meanwhile, the quantum circuits and some examples of scrambling are given. Furthermore, various analyses of the performance of this scheme were conducted, including effectiveness, key space, and computational complexity. By modifying the random generation factor to construct multiple binary grayscale images, the simulated results on the IBM Quantum Cloud platform demonstrate that the proposed quantum image encryption scheme is effective. In comparison to existing quantum image dual scrambling schemes, it is both simple and effective, offering a large key space, lower computational complexity, and applicability to non-square quantum images. [ABSTRACT FROM AUTHOR]

The article "Demystifying Quantum" discusses two key quantum developments in cybersecurity: post-quantum cryptography (PQC) and quantum key distribution (QKD). PQC addresses the threat posed by quantum computing to classical algorithms like RSA, while QKD ensures secure key exchange. The article highlights the differences between PQC and QKD in mitigating the risk of quantum computers breaking RSA encryption. It also discusses the challenges and implications of implementing quantum-based solutions in cryptographic systems. [Extracted from the article]

The article discusses the impact of quantum computing on current cryptographic systems and the need for organizations to prepare for the transition to quantum-safe cryptography. It highlights the risks of impersonation and forgery that may arise with quantum computing and emphasizes the importance of early awareness and education at all levels of an organization. The article also addresses the need for thorough planning, risk evaluation, and contingency plans to address potential data exposure or impersonation due to migration gaps. Additionally, it mentions the importance of understanding the implications of quantum computing on cybersecurity insurance and the need for organizations to work with insurers to ensure adequate coverage. [Extracted from the article]

In this paper, we perform a cryptanalysis of a previously published symmetric cryptosystem that utilizes the Arnold transform (AT), singular value decomposition (SVD), and the fractional Hartley transform (FrHT) domain. By performing an attack-analysis, it is shown that the symmetric cryptosystem is vulnerable to a Known-Plaintext Attack (KPA). If an attacker knows the cipher-text and the order of the FrHT, attacker can recover the correct combination of SVD and AT parameters used in the image encryption algorithm. To overcome the security weakness of the symmetric cryptosystem, we propose an asymmetric phase image encryption by employing the Arnold transform, Singular value decomposition, and Hessenberg decomposition (HD) in the FrHT domain. The scheme is validated using evaluation metrics; mean-square-error, peak signal-to-noise, entropy, 3D mesh-, correlation-, noise-attack-, occlusion-attack-, and linear-attack analyses. Keys generated by SVD and HD make the cryptosystem asymmetric, making it resistant to Known-Plaintext Attack (KPA) and Chosen-Plaintext Attack (CPA). [ABSTRACT FROM AUTHOR]

Due to their inherent openness, wireless sensor networks (WSNs) are vulnerable to eavesdropping attacks. Addressing the issue of secure Internet Key Exchange (IKE) in the absence of reliable third parties like CA/PKI (Certificate Authority/Public Key Infrastructure) in WSNs, a novel key synchronization method named NDPCS-KS is proposed in the paper. Firstly, through an initial negotiation process, both ends of the main channels generate the same initial key seeds using the Channel State Information (CSI). Subsequently, negotiation keys and a negative database (NDB) are synchronously generated at the two ends based on the initial key seeds. Then, in a second-negotiation process, the NDB is employed to filter the negotiation keys to obtain the keys for encryption. NDPCS-KS reduced the risk of information leakage, since the keys are not directly transmitted over the network, and the eavesdroppers cannot acquire the initial key seeds because of the physical isolation of their eavesdropping channels and the main channels. Furthermore, due to the NP-hard problem of reversing the NDB, even if an attacker obtains the NDB, deducing the initial key seeds is computationally infeasible. Therefore, it becomes exceedingly difficult for attackers to generate legitimate encryption keys without the NDB or initial key seeds. Moreover, a lightweight anti-replay and identity verification mechanism is designed to deal with replay attacks or forgery attacks. Experimental results show that NDPCS-KS has less time overhead and stronger randomness in key generation compared with other methods, and it can effectively counter replay, forgery, and tampering attacks. [ABSTRACT FROM AUTHOR]

Since the existing tropical cryptographic protocols are either susceptible to the Kotov-Ushakov attack and its generalization, or to attacks based on tropical matrix periodicity and predictive behavior, several attempts have been made to propose protocols that resist such attacks. Despite these attempts, many of the proposed protocols remain vulnerable to attacks targeting the underlying hidden problems, one of which we call the tropical two-sided discrete logarithm with shift. An illustrative case is the tropical Stickel protocol, which, when formulated with a single monomial instead of a polynomial, becomes susceptible to attacks based on solutions of the above mentioned tropical version of discrete logarithm. In this paper we will formally introduce the tropical two-sided discrete logarithm with shift, discuss how it is solved, and subsequently demonstrate an attack on a key exchange protocol based on the tropical semiring of pairs. This particular protocol is compromised due to the existence of efficient (albeit heuristic) solution of the tropical two-sided logarithm problem, and this highlights the ongoing challenges in search of a "good" key exchange protocol in tropical cryptography. [ABSTRACT FROM AUTHOR]

This paper presents the first functional encryption (FE) scheme for the attribute-weighted sum functionality that supports the uniform model of computation. In such an FE scheme, encryption takes as input a pair of attributes (x, z) where x is public and z is private. A secret key corresponds to some weight function f, and decryption recovers the weighted sum f(x)z. In our scheme, both the public and private attributes can be of arbitrary polynomial lengths that are not fixed at system setup. The weight functions are modelled as Logspace Turing machines . Prior schemes could only support non-uniform Logspace. The proposed scheme is proven adaptively simulation secure under the well-studied symmetric external Diffie–Hellman assumption against an arbitrary polynomial number of secret key queries both before and after the challenge ciphertext. This is the best possible security notion that could be achieved for FE. On the technical side, our contributions lie in extending the techniques of Lin and Luo [EUROCRYPT 2020] devised for indistinguishability-based payload hiding attribute-based encryption for uniform Logspace access policies and the "three-slot reduction" technique for simulation-secure attribute-hiding FE for non-uniform Logspace devised by Datta and Pal [ASIACRYPT 2021] to the context of simulation-secure attribute-hiding FE for uniform Logspace. [ABSTRACT FROM AUTHOR]

Whether you are just starting to teach cryptography, or you teach it as a stand-alone course for computer science majors or as part of a complete major in cybersecurity, the question of how to provide hands-on experience is an important one. Some software may be too expensive, while other schemes only allow students to use small, toy examples. Here, a solution using a software package called bigint is examined. It can allow students to implement, try out, and try to break C++ implementations of most common public key cryptographic algorithms. Better yet, bigint is free and will run under Linux, which is often free as well. Thus, with this free software, students can implement common cryptographic algorithms, using large numbers instead of tiny ones, time how long the computations take, and investigate where the algorithms fail to work well -- the sort of exercises that help students more fully understand this technical and rapidly-changing field. [ABSTRACT FROM AUTHOR]

The field of cryptography has grown significantly with the advent of information and communication technologies due to the increasing complexity of cyber threats and rising security requirements. This evolution has come with the creation of new cryptosystems and improvements to current ones. This study is the first to explore the RSA approach in the framework of t-intuitionistic fuzzy subgroups. This technique makes group-based cryptographic operations safer when there are unclear relationships and hesitations. This supports the complex and uncertain nature of subgroup membership, allowing for much more significant representations of the degrees of belonging, non-belonging, and hesitancy for the group elements along parameter 't'. The t-intuitionistic fuzzy RSA technique employs a t-intuitionistic fuzzy subgroup to address cryptosystem ambiguity, fuzziness, and imprecision. Consequently, inaccurate cryptographic data is more effectively represented, manipulated, and protected. Furthermore, this technique enhances the current level of fuzzy cryptography. The t-intuitionistic fuzzy RSA algorithms are of theoretical and practical value, as they significantly contribute towards developing fuzzy cryptography, fuzzy algebraic structures, and decision support systems. In this paper, the notions of t-intuitionistic fuzzy numbers and triangular t-intuitionistic fuzzy numbers are introduced. A new RSA cryptosystem based on a t-intuitionistic fuzzy subgroup is proposed in which the plaintext and the ciphertext are obtained in terms of t-intuitionistic fuzzy numbers and triangular t-intuitionistic fuzzy numbers. In addition, the significance of the concept of the t-intuitionistic fuzzy subgroup is highlighted as a suitable alternative tool to secure the data under consideration. In addition, the practical effect of the proposed methods is also investigated in this study. A mathematical mechanism is presented to implement the t-intuitionistic fuzzy RSA algorithm. Finally, a comparative analysis of the developed technique is presented with some existing methods to showcase the applicability and superiority of the recently developed method. [ABSTRACT FROM AUTHOR]

As the main inter-domain routing protocol in today's internet, the Border Gateway Protocol (BGP) faces serious security risks during actual usage. Research on BGP malicious attack methods requires a realistic network environment, and evaluation methods based on physical networks often suffer from high costs and insufficient flexibility. Thus, we propose an efficient BGP simulated network deployment system based on a virtualization technology called the SOD–BGP. This system, combining cloud computing and virtualization technologies, creates a scalable, highly flexible basic network environment that allows for the automated simulation and evaluation of actual BGP prefix hijacking attack scenarios. A Resource Public Key Infrastructure (RPKI) simulation suite is introduced into the system, emulating a certificate issuance system, certificate storage, and a certificate synchronization verification mechanism, thus aligning the simulation environment with real-world usage scenarios. Finally, we propose a data collection and performance evaluation technique to evaluate BGP networks deploying RPKI under different attack scenarios and to explore the effectiveness of RPKI defense mechanisms at various deployment rates. A comparative analysis with other simulation techniques demonstrates that our approach achieves a balanced performance in terms of deployment speed, complexity, and RPKI integrity, providing a solid simulation technology foundation for large-scale BGP security defense strategies. [ABSTRACT FROM AUTHOR]

The advancements in quantum computing and the potential for polynomial-time solutions to traditional public key cryptography (i.e., Rivest–Shamir–Adleman (RSA) and elliptic-curve cryptography (ECC)) using Shor's algorithm pose a serious threat to the security of pre-quantum blockchain technologies. This paper proposes an efficient quantum-safe blockchain that incorporates new quantum-safe consensus algorithms. We integrate post-quantum signature schemes into the blockchain's transaction signing and verification processes to enhance resistance against quantum attacks. Specifically, we employ the Falcon signature scheme, which was selected during the NIST post-quantum cryptography (PQC) standardization process. Although the integration of the post-quantum signature scheme results in a reduction in the blockchain's transactions per second (TPSs), we introduce efficient approaches to mitigate this performance degradation. Our proposed post-quantum delegated proof of luck (PQ-DPoL) combines a proof of luck (PoL) mechanism with a delegated approach, ensuring quantum resistance, energy efficiency, and fairness in block generation. Experimental results demonstrate that while post-quantum cryptographic algorithms like Falcon introduce larger signature sizes and slower processing times, the PQ-DPoL algorithm effectively balances security and performance, providing a viable solution for secure blockchain operations in a post-quantum era. [ABSTRACT FROM AUTHOR]

Current authentication schemes based on zero-knowledge proof (ZKP) still face issues such as high computation costs, low efficiency, and security assurance difficulty. Therefore, we propose a secure and efficient authentication scheme (SEAS) for large-scale IoT devices based on ZKP. In the initialization phase, the trusted authority creates prerequisites for device traceability and system security. Then, we propose a new registration method to ensure device anonymity. In the identity tracing and revocation phase, we revoke the real identity of abnormal devices by decrypting and updating group public keys, avoiding their access and reducing revocation costs. In the authentication phase, we check the arithmetic relationship between blind certificates, proofs, and other random data. We propose a new anonymous batch authentication method to effectively reduce computation costs, enhance authentication efficiency, and guarantee device authentication security. Security analysis and experimental results show that an SEAS can ensure security and effectively reduce verification time and energy costs. Its security and performance exceed existing schemes. [ABSTRACT FROM AUTHOR]

Due to the similar characteristics of chaotic systems and cryptography, public key encryption algorithms based on chaotic systems are worth in-depth research and have high value for the future. Chebyshev polynomials have good properties and are often used in the design of public key algorithms. This paper improves the Bose Multi-Chaotic Public Key Cryptographic Algorithm (BMPKC) by applying Chebyshev polynomials. The proposed algorithm (CMPKC- k i ) introduces the selective coefficient k i based on the properties of Chebyshev polynomials, allowing the special functions that need to be negotiated in the original system to be freely and randomly chosen as Chebyshev polynomials, and can also be expanded to m levels. The improved cryptographic algorithm also utilizes chaotic hash functions and logistic mapping to generate pseudo-random sequences and overcomes shortcomings of the Bose algorithm by iteratively iterating the selected Chebyshev polynomials based on the number of 0s or 1s in the pseudo-random sequence, thus providing better security. Analysis and software testing results indicate that this algorithm has strong robustness against brute force attacks, achieving a higher attack time for breaking the private key compared to the CEPKC, BMPKC, and CMPKC algorithms. Compared to the CMPKC algorithm, our proposal algorithm achieves better performance in the encryption and decryption phases. Furthermore, we combine this Multi-Chaotic System Key Exchange Protocol with the Advanced Encryption Standard (AES) algorithm, while providing a demonstration, offering more possibilities for practical applications of this system. [ABSTRACT FROM AUTHOR]

One of the main trends for the monitoring and control of business processes is to implement these processes via private blockchain systems. These systems must ensure data privacy and verifiability for the entire network here denoted by 'Net'. In addition, every business activity should be declared to a trusted third party (TTP), such as an Audit Authority (AA), for tax declaration and collection purposes. We present a solution for a confidential and verifiable realization of transactions based on the Unspent Transaction Output (UTxO) paradigm. This means that the total sum of transaction inputs (incomes) I n must be equal to the total sum of transaction outputs (expenses) E x , satisfying the balance equation I n = E x. Privacy in a private blockchain must be achieved through the encryption of actual transaction values. However, it is crucial that all participants in the network be able to verify the validity of the transaction balance equation. This poses a challenge with probabilistically encrypted data. Moreover, the inputs and outputs are encrypted with different public keys. With the introduction of the AA, the number of different public keys for encryption can be reduced to two. Incomes are encrypted with the Receiver's public key and expenses with the AA's public key. The novelty of our realization lies in taking additively-multiplicative, homomorphic ElGamal encryption and integrating it with a proposed paradigm of modified Schnorr identification providing a non-interactive zero-knowledge proof (NIZKP) using a cryptographically secure h-function. Introducing the AA as a structural element in a blockchain system based on the UTxO enables effective verification of encrypted transaction data for the Net. This is possible because the proposed NIZKP is able to prove the equivalency of two ciphertexts encrypted with two different public keys and different actors. This integration allows all users on the Net to check the UTxO-based transaction balance equation on encrypted data. The security considerations of the proposed solution are presented. [ABSTRACT FROM AUTHOR]

In recent years, research on attribute-based encryption (ABE) has expanded into the quantum domain. Because a traditional single authority can cause the potential single point of failure, an improved lattice-based quantum-resistant identity authentication and policy attribute encryption scheme is proposed, in which the generation of random values is optimized by adjusting parameters in the Gaussian sampling algorithm to improve overall performance. Additionally, in the key generation phase, attributes are processed according to their shared nature, which reduces the computational overhead of the authorization authority. In the decryption phase, the basis transformation of the Lenstra–Lenstra–Lovász (LLL) lattice reduction algorithm is utilized to rapidly convert shared matrices into the shortest vector form, which can reduce the computational cost of linear space checks. The experimental results demonstrate that the proposed method not only improves efficiency but also enhances security compared with related schemes. [ABSTRACT FROM AUTHOR]

With the increasing awareness for sustainable future and green energy, the demand for electric vehicles (EVs) is growing rapidly, thus placing immense pressure on the energy grid. To alleviate this, local trading between EVs should be encouraged. In this paper, we propose a blockchain and public key infrastructure (PKI)-based secure vehicle-to-vehicle (V2V) energy-trading protocol. A permissioned blockchain utilizing the proof of authority (PoA) consensus and smart contracts is used to securely store data. Encrypted communication is ensured through transport layer security (TLS), with PKI managing the necessary digital certificates and keys. A multi-leader, multi-follower Stackelberg game-based trade algorithm is formulated to determine the optimal energy demands, supplies, and prices. Finally, we propose a detailed communication protocol that ties all the components together, enabling smooth interaction between them. Key findings, such as system behavior and performance, scalability of the trade algorithm and the blockchain, smart contract execution costs, etc., are presented through numerical results by implementing and simulating the protocol in various scenarios. This work not only enhances local energy trading among EVs, encouraging efficient energy usage and reducing burden on the power grid, but also paves a way for future research in sustainable energy management. [ABSTRACT FROM AUTHOR]

With the escalation of multimedia data, cloud technology has played a very important role in its management with its promising computing and storage capabilities. Cloud computing leverages high scalability, resources, and on-demand services, which have a remarkable impact on assisting multimedia data storage. Meanwhile, any alteration in the outsourced multimedia data is a severe menace. Numerous researchers have focused on providing validation of integrity through the auditing mechanism. Regrettably, their mechanisms are focused on the traditional public-key cryptosystem and cannot withstand quantum attacks. Additionally, the centralised approach of completely relying on a third-party auditor (TPA) of existing mechanisms may lead to biased auditing results. Hence, employing the advantage of resistance against quantum attack and removing the liability of certificates with lattice cryptography and an identity-based cryptosystem, we have presented a new auditing framework by utilising blockchain technology. Blockchain technology is employed in order to track the activities of the cloud service provider and TPA, resulting less dependency on TPA. Security analysis portrays security of the framework under the random oracle model, which depends is based on the Shortest Integer Solution (SIS) problem of the lattices. Reduced computation, communication and storage overheads with efficient features and performance is observed for the proposed mechanism through analysis conducted with similar mechanisms. As a result, better operability is achieved by the proposed mechanism. [ABSTRACT FROM AUTHOR]

In fifth-generation (5G)-based vehicular networks, vehicles share information about the road's condition to make driving safer and alleviate traffic congestion. Given the public nature of the medium, addressing issues of confidentiality and security is of paramount importance. Existing systems are vulnerable to a distributed denial-of-service (DDoS) attack from an attacker or high traffic in a dense area because of the time-consuming and complex operations based on bilinear pair and elliptic curve cryptographies used. In order to protect vehicle-to-vehicle communication in 5G-based vehicular networks from DDoS attacks, a strategy based on the Chebyshev polynomial is proposed in this study. The semi-group and chaotic features of the Chebyshev polynomial are utilised in our proposal. Our solutions also meet all applicable standards for security and privacy, such as node authentication, message integrity, preserving identity privacy, traceability, unlinkability, and resistance to attacks. Finally, our innovation decreases the computational burden to produce a message signature by 66.67% and the burden to verify a signature by 33.33%. However, the size of the message-signature tuple is affected by the communication expenses of our work by 5.00%. [ABSTRACT FROM AUTHOR]

Proxy signature schemes can be used in all the scenarios where a signer is not able to sign an important message. In some cases which involve a group of proxy signers, the anonymity of the proxy signer is required. We propose the first multivariate anonymous proxy signature scheme over finite field, and discuss all its security properties such as anonymity, unforgeability, verifiability, distinguishability, and undeniability. Additionally, we give a toy example to demonstrate the mathematical functioning of the proposed scheme. We compare our scheme with the existing post-quantum anonymous proxy signature scheme. [ABSTRACT FROM AUTHOR]

Double auction provides a cost-effective manner for sellers/buyers in smart grid. Due to concerns about information leakage, the asks/bids from sellers/buyers are sealed, making it challenging to select potential winners. To address this problem, the concept of public key encryption with equality test is deployed in double auction, since it is able to perform information retrieval over secure asks/bids. However, previous solutions suffer from the following two limitations: (i) unable to check inconsistent secure asks/bids due to the lack of tester-verifiable mechanism; (ii) incurring high matching time costs caused by one-to-one secure asks/bids. Therefore, we propose the VerDA, a secure double auction retrieval system with verifiable equality retrieval towards multiple secure asks/bids. Technically, to achieve the property of consistency over secure asks/bids, we develop the tester-verifiable technology by combining the decryption module and test module. To improve the efficiency of retrieval, we introduce secure multi-asks/bids testing function by augmenting the number of inputs in a same retrieval process. Moreover, we implement VerDA based on the PJM dataset in real cloud environment, where the experimental results show practical performance with encryption and test costs amounting to only 57.4% and 18.7% compared to state-of-the-art solution. [ABSTRACT FROM AUTHOR]

Featured Application: The work may find applications in secure coordination and self-management of groups of unmanned underwater vehicles (UUVs). We consider authenticating multicast messages in the case of extremely narrow communication channels, such as underwater acoustic communication, with devices such as mobile sensors creating a self-organizing autonomous network. Channel characteristics in this scenario prevent the application of digital signatures (and asymmetric cryptography in general), as it would consume too much of the available bandwidth. As communication is relatively sparse, standard symmetric methods such as TESLA have limited application in this scenario as well. Driven by real-world requirements, we focus on tiny networks of only a few nodes. This paper discusses two issues: (a) strategies of key predistribution enabling flexible creation of multicast groups; (b) authenticating multicast messages in a way that prevents an attacker impersonating the sender by subverting one or more receiver nodes and learning the symmetric keys stored by these nodes. For tiny networks, we show that scalable and asymptotically efficient solutions might be useless, and that specially tailored combinatorial approaches may confer some advantage. [ABSTRACT FROM AUTHOR]

The Industrial Internet of Things (IIoT) consists of massive devices in different management domains, and the lack of trust among cross-domain entities leads to risks of data security and privacy leakage during information exchange. To address the above challenges, a viable solution that combines Certificateless Public Key Cryptography (CL-PKC) with blockchain technology can be utilized. However, as many existing schemes rely on a single Key Generation Center (KGC), they are prone to problems such as single points of failure and high computational overhead. In this case, this paper proposes a novel blockchain-based certificateless cross-domain authentication scheme, that integrates the threshold secret sharing mechanism without a trusted center, meanwhile, adopts blockchain technology to enable cross-domain entities to authenticate with each other and to negotiate session keys securely. This scheme also supports the dynamic joining and removing of multiple KGCs, ensuring secure and efficient cross-domain authentication and key negotiation. Comparative analysis with other protocols demonstrates that the proposed cross-domain authentication protocol can achieve high security with relatively low computational overhead. Moreover, this paper evaluates the scheme based on Hyperledger Fabric blockchain environment and simulates the performance of the certificateless scheme under different threshold parameters, and the simulation results show that the scheme has high performance. [ABSTRACT FROM AUTHOR]

As with IoT devices, cloud computation increases its applicability to other areas that use the information and puts it in a commonplace that is necessary for computing and analysis. These devices need the cloud to store and retrieve data since they are unable to store and process data on their own. Cloud computing offers a variety of services to consumers, including IaaS, PaaS, and SaaS. The usage of cloud resources for data storage that may be accessible by all users associated with cloud computing is a key disadvantage of cloud computing. Without disclosing the data's contents, the usage of Public Key Encryptions with Keyword Search (PEKS) secures publicly encrypted keys against third-party search capabilities that are not trustworthy. PEKs provide a security risk every time Interior Keywords Guessing Attacks (IKGA) are discovered in the system since an unauthorized service estimates the keywords in the trapdoor. This issue can be resolved using various methodologies such as the Certificateless Fleshed Public Key Authenticated Encryption of Keyword Search (CL-HPAEKS), which also uses Altered Elliptic Curve Cryptography (MECC), and the Mutation Centred Flower Pollinations Algorithm (CM-FPA), which uses optimization in keys to be improving the algorithm's performance. The system's security is achieved by adding a Message Fragments 5 (MD5) scramble mechanism. The proposed system achieves system security of 96%, and it takes less time to implement than earlier encryption methods. [ABSTRACT FROM AUTHOR]

Wireless sensor networks (WSNs) are widely acknowledged for their potential as a robust infrastructure for collecting, processing, and transmitting information. Rezaeipour & Barati proposed a hierarchical key management scheme that manages key creation, distribution, and maintenance to provide services like message confidentiality, integrity, and authenticity to wireless sensor networks. As per the assertions posited by the authors, their scheme purportedly exhibits resilience against a spectrum of potential threats. Nevertheless, upon subjecting their scheme to meticulous scrutiny, our analysis revealed vulnerabilities to manifold adversarial strategies, notably including man-in-the-middle attacks, replay attacks, impersonation attacks, and node capture attacks. This scheme fails to establish a secure session key agreement also. In response to these identified shortcomings, this research devised an "Improved Hierarchical Key Management" (IHKM) Scheme aimed at rectifying the deficiencies of Rezaeipour and Barati's scheme (RB scheme). This work proposed an enhanced key management scheme that utilizes a blend of symmetric and asymmetric key cryptography to enhance the security parameters of Hierarchical WSNs. A comprehensive security analysis of the proposed work shows that the IHKM scheme is secure against impersonation attacks, man-in-the-middle attacks, replay attacks node capture attacks, Denial-of-Service attacks, and base station bypassing attacks while establishing the mutual key agreement between the area managers and sensor nodes. Moreover, a comparative analysis of the IHKM scheme exhibits notable reductions in energy consumption (62.27% and 49.15%) and memory utilization (39.28%, 23.36%) when compared with the RB scheme and HISCOM schemes respectively. Simultaneously, IHKM contributes to the extension of the network's overall lifespan by 48.78% as compared to HISCOM scheme and 32.63% as compared to compared with the RB scheme, thereby enhancing the efficiency and longevity of the WSN infrastructure. [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]

Fully homomorphic encryption (FHE) is capable of handling sensitive encrypted data in untrusted computing environments. The efficient application of FHE schemes in secure outsourced computation can effectively address security and privacy concerns. This paper presents a novel fully homomorphic encryption scheme called GMS, based on the n-secret learning with errors (LWE) assumption. By utilizing block matrix and decomposition technology, GMS achieves shorter encryption and decryption times and smaller ciphertext sizes compared to existing FHE schemes. For secure outsourced matrix multiplication A m × n · B n × l with arbitrary dimensions, GMS only requires O (max { m , n , l }) rotations and one homomorphic multiplication. Compared to the state-of-the-art methods, our approach stands out by achieving a significant reduction in the number of rotations by a factor of O (log max { n , l }) , along with a decrease in the number of homomorphic multiplications by a factor of n and O (min { m , n , l }) . The experimental results demonstrate that GMS shows superior performance for secure outsourced matrix multiplication of any dimension. For example, when encrypting a 64 × 64 -dimensional matrix, the size of the ciphertext is only 1.27 MB. The encryption and decryption process takes approximately 0.2 s. For matrix multiplication A 64 × 64 · B 64 × 64 , the runtime of our method is 39.98 s, achieving a speedup of up to 5X and 2X. [ABSTRACT FROM AUTHOR]

Fog computing is a revolutionary technology that, by expanding the cloud computing paradigm to the network edge, brings a significant achievement in the resource-constrained IoT applications in intelligent environments. However, security matters still challenge the extensive deployment of fog computing infrastructure. Ciphertext policy attribute-based encryption prepares a solution for data sharing and security preservation issues in fog-enhanced intelligent environments. Nevertheless, the lack of an effective mechanism to moderate the execution time of CP-ABE schemes due to the diversity of attributes used in secret key and access structure, as well as ensuring data security, practically restricts the deployment of such schemes. In this regard, a collaborative semantic model, including an outsourced CP-ABE scheme with the attribute revocation ability, together with an impressive AES algorithm relying on an ensemble learning system, was proposed in this study. The ensemble learning model uses multiple classifiers, including the GMDH, SVM, and KNN, to specify attributes corresponding to CP-ABE. The Dragonfly algorithm with a semantic leveling method generates outstanding and practical feature subsets. The experimental results on five smart building datasets indicate that the recommended model performs more accurately than existing methods. Also, the encryption, decryption, and attribute revocation execution time are significantly modified with the average time of 1.95, 2.11, and 14.64 ms, respectively, compared to existing works and conducted the scheme's security. [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]

Industrial Internet of Things (IIoT) is a pivotal driving force behind the intelligent transformation of the global industrial system, bringing about a gradual shift in production methods. However, due to users completing remote access and data transmission through open channels, ensuring user legitimacy and data security has become an important factor in IIoT. In addition, resource limited users or devices need to collect and publish corresponding messages while also timely processing instant messages obtained from the network. Leveraging edge computing technology effectively mitigates the transmission time of messages, addressing the challenges of high computing pressure and prolonged response time associated with cloud server computing. Therefore, investigating authentication key agreement based on edge computing in the IIoT environment holds substantial theoretical significance and practical importance. This article introduces an IIoT authentication that ensures both security and efficiency by integrating elliptic curve cryptography and three-factor authentication. Within this scheme, the user and the edge server accomplish security authentication. Through security analysis, the proposed scheme is proven to meet the essential security requirements. Performance analysis shows that it achieves higher security, supports more functions, and achieves lower computational and communication costs compared to related schemes. [ABSTRACT FROM AUTHOR]

The need for high-quality healthcare services increases to more incredible speeds. Smart healthcare offers an ecosystem of IoT wireless networks, computers and software applications to enable medical tracking, mobility and emergency services through smart wearables. In this ecosystem, security attacks are continuously arisen and sensitive medical data are threatened. Strong cryptographic mechanisms are then crucial for securely processing smart healthcare data. Previously, traditional public key cryptosystems are utilized to address security concerns pertaining to healthcare sector. These cryptosystems provide security under hard problems like discrete logarithmic problem and bilinear pairing which are vulnerable to quantum attacks. In recent years, lattice-based cryptography (LBC) has emerged as a quantum-safe substitute to traditional public-key cryptosystems. In this context, we present a hierarchical healthcare structure where intra-cluster and inter-cluster communication patterns are defined. Then, we propose a security design based on LBC. For intra-cluster communications, a certificateless identity-based Diffie–Hellman key exchange protocol secure under learning with errors hard problem over lattices is designed. It is composed of a registration phase, login phase and a key agreement scheme. To ensure trust, security and interoperability between different healthcare stakeholders defining the inter-cluster communication pattern, post-quantum Blockchain technology is used. Dilithium lattice-based signature scheme is proposed to replace the current ECDSA blockchain signature scheme. The communication and computation costs of the proposed key agreement protocol has been evaluated in comparison with the traditional ECDH-ECDSA key exchange scheme and to an authenticated version of a post-quantum key agreement scheme named SIKE-Dilithium. The obtained results prove the efficacy of our proposal. Moreover, through security analysis, we have demonstrated that the proposed security design ensures security requirements of healthcare application and can effectively resist quantum and classical attacks. [ABSTRACT FROM AUTHOR]

The paper addresses the issue of secure distribution of codebooks in the field of information security, particularly in the domain of covert communication. We propose a codebook distribution technique based on secret sharing. Secret sharing is a method of dividing and storing secrets that can withstand certain levels of external intrusion and internal deception. In this technique, the sender encrypts the codebook using a private key and uploads it to the IPNS. Each recipient can then obtain the public key for downloading the codebook through a mechanism based on password-protected secret sharing. Based on experimental results and security analysis, the scheme exhibits high time efficiency and stable memory usage. Furthermore, it can withstand various attacks, ensuring the security of codebook transmission. [ABSTRACT FROM AUTHOR]

The security of the global Certification Authority (CA) system has recently been compromised as a result of attacks on the Public Key Infrastructure (PKI). Although the CA/Browser (CA/B) Forum publishes compliance requirements for CAs, there are no guarantees that even a commercially successful CA is complying with these recommendations. In this paper, we propose the first systematic CA ranking mechanism that ranks CAs in terms of their adherence to the CA/B Forum and X.509 certificate standards. Unfortunately, there is no consolidated and widely accepted parameter to rank the CAs so we have proposed formula-based rating models and introduced different ranking techniques like Direct, Bayesian, and MarkovChain Ranking. These rankings are applied to a comprehensive dataset of X.509 trust chains gathered during the time period of 2020 to 2023. Our proposed ranking scheme can serve as a criterion for both consumers and enterprises for selecting and prioritizing CAs based on performance as well as adherence to the certificate standards. [ABSTRACT FROM AUTHOR]

In the current landscape where quantum algorithms pose a significant threat to conventional digital signature algorithms, code-based digital signature algorithms have emerged as the primary focus of ongoing research in post-quantum cryptography. Digital signatures play a pivotal role in ensuring non-repudiation and authentication, making them an indispensable cryptographic technique. The vulnerability of most digital signature algorithms to quantum attacks have prompted a significant surge in research on code-based digital signature algorithms, which have emerged as a prominent field within post-quantum cryptography. There are generally three distinct approaches to constructing code-based digital signature algorithms: (1) Developing an algorithm that follows the inverse process of the code-based public-key encryption algorithm; (2) Utilizing zero-knowledge identification algorithms in conjunction with the Fiat–Shamir paradigm to formulate a signature algorithm; (3) Constructing a specialized subset of the syndrome space as the foundation for the digital signature algorithm. Chameleon Signature is a non-interactive signature that operates on the hash and signature paradigm, exhibiting comparable efficiency to conventional schemes. Its distinct advantage lies in the fact that the owner of the public key does not necessarily require access to the corresponding secret key within the Chameleon hash algorithm. Notably, Chameleon signatures possess an inherent characteristic of non-transferability, with their validity ascertainable solely by designated recipients. This paper introduces the first Chameleon hash function based on both KKS and HFE schemes, showcasing its superiority over traditional schemes through rank metrics and big fields for enhanced security. The deployment of Chameleon hash functions within hash-and-sign signature schemes introduces a nuanced layer of security and verification flexibility. This study elucidates the implications of integrating Chameleon hash functions into the recipient's public key infrastructure, highlighting the dual capability it affords authorized parties for secure and adaptable verification processes, alongside mechanisms for the detection of unauthorized alterations. [ABSTRACT FROM AUTHOR]

The concept of security is quite broad and touches the lives of one million people on a daily basis. Those individuals who depend on networks for activities such as banking, shopping, and filing their tax returns may soon face a potentially significant challenge in the form of network security, which will need to be handled in the not-too-distant future. The solution that is being recommended is a combination of two algorithms: The Hybrid Rivest–Shamir–Adleman (RSA) algorithm and the Ant Lion Optimization Algorithm. There have been two noteworthy developments in the requirements for information security inside a wireless sensor network over the course of the last several decades. First, prior to the broad use of data processing equipment, the security of information that was regarded useful to a wireless sensor network was largely supplied by physical and administrative precautions. This was the case even after the widespread use of data processing equipment. Hash functions are used by these designs whenever Rebalanced RSA is used to encrypt a message. This helps to guarantee that the integrity of the message is not compromised in any way. It has been found out that this novel method is susceptible to attacks based on selected ciphertext as well as adaptive attacks based on chosen ciphertext. A second strategy, which entails converting the ciphertext into binary format, is also one of the options that are being investigated. The binary format is further compressed and coded, which makes it resistant to a variety of attacks, including adaptive chosen ciphertext assaults, selected ciphertext assaults, and other assaults. To get started, a thorough study project on mapping is carried out in order to establish the mapping of assaults and counterattacks that would be most effective. A brand-new index that goes by the name "Threat Severity Index" (TSI) has been developed with the intention of determining how secure each individual system is on the whole. In addition, the decryption performance of RSA-type cryptosystems is researched and compared with that of other RSA-type cryptosystems in order to identify which cryptosystem provides the quickest decryption time. Last but not least, an overall rating of each system is provided, taking into account both its speed and its level of safety. [ABSTRACT FROM AUTHOR]

This paper analyzes two schemes from a 2019 work by Liu, Yang, Han and Wang, namely, adapting the McEliece cryptosystem to obtain a new public-key encryption scheme, and designing an efficient CFS-like digital signature. It is shown that the new encryption scheme based on McEliece, even if it has longer public keys, is not more secure than the standard one. The security gap between the original scheme and its modification is presented. Moreover, while the proposed parameters for the digital signature scheme lead to a significant performance improvement, however, they introduce a vulnerability in the protocol. A key-forgery attack using the Support Splitting Algorithm as a subroutine is described, with a study of the computational cost of retrieving the secret key from the public one. [ABSTRACT FROM AUTHOR]

Robust subgroup multisignature allows any subgroup of signers from a global set to sign a given message on behalf of the whole group, and the individual signatures should be verified before the combination process, which resists poison signature attacks. An emerging application of robust subgroup multisignatures in blockchain is that a qualified subgroup of a global set of users has reached agreement. In the integrated blockchain and edge computing system, the edge server can naturally act as a combiner in multisignatures and help other end devices produce the final aggregate signature. In this paper, we propose a robust subgroup multisignature with one-time public keys in order that has two advantages for solving the signers ordering problem and one-time public key problem simultaneously. Our scheme is a nontrivial extension of Galindo et al.'s robust subgroup multisignature scheme and can be proven unforgeable, robust and chronological in random oracles. Our scheme can also be suitable for the consortium blockchain by adding a noninteractive zero-knowledge (NIZK) proof system for certifying the one-time public keys. [ABSTRACT FROM AUTHOR]

In recent years, with the rapid development of blockchain technology, the issues of storage load and data security have attracted increasing attention. Due to the immutable nature of data on the blockchain, where data can only be added and not deleted, there is a significant increase in storage pressure on blockchain nodes. In order to alleviate this burden, this paper proposes a blockchain data storage strategy based on a hot and cold block mechanism. It employs a block heat evaluation algorithm to assess the historical and correlation-based heat indicators of blocks, enabling the identification of frequently accessed block data for storage within the blockchain nodes. Conversely, less frequently accessed or "cold" block data are offloaded to cloud storage systems. This approach effectively reduces the overall storage pressure on blockchain nodes. Furthermore, in applications such as healthcare and government services that utilize blockchain technology, it is essential to encrypt stored data to safeguard personal privacy and enforce access control measures. To address this need, we introduce a blockchain data encryption storage mechanism based on threshold secret sharing. Leveraging threshold secret sharing technology, the encryption key for blockchain data is fragmented into multiple segments and distributed across network nodes. These encrypted key segments are further secured through additional encryption using public keys before being stored. This method serves to significantly increase attackers' costs associated with accessing blockchain data. Additionally, our proposed encryption scheme ensures that each block has an associated encryption key that is stored alongside its corresponding block data. This design effectively mitigates vulnerabilities such as weak password attacks. Experimental results demonstrate that our approach achieves efficient encrypted storage of data while concurrently reducing the storage pressure experienced by blockchain nodes. [ABSTRACT FROM AUTHOR]

In the quantum era, the advent of quantum computers poses significant threats to the security of current cryptosystems. Therefore, designing quantum-resistant cryptoschemes becomes important to guarantee information security. This work concentrates on the development of the postquantum public key encryption (PKE) scheme. Non-commutative cryptography (NCC) has entered the field of post-quantum cryptography. We utilize the TSPEM problem with asymmetric structures (which serve as a potential candiate for resisting quantum attacks) to construct two PKE schemes which are demonstrated to be CPA security under the DTSPEM assumption. By representing the plaintext as a matrix, these schemes can effectively encrypt a significant amount of information in a single operation. Assuming an equal amount of messages for encryption, the proposed schemes acheive superior efficiency compared to existing PKE schemes. Structurally, our systems exhibit a level of synchronization and coexistence due to the distinct public keys (P) and ciphertexts (C1). The efficiency analysis is conducted by comparing known schemes from the aspect of specific cryptographic indicators. Generally, the proposed ones offer several advantages including provable security, high efficiency, potential quantum-resistant, and relative ease of implementation; along with synchronization and coexistence. Our investigation has established the feasibility of constructing PKE schemes based on the TSPEM problem, specifically for asymmetric communication scenarios. The preliminary results pave the way for further exploration of the TSPEM problem's potential in developing other cryptosystems suitable for quantum computing environments. [ABSTRACT FROM AUTHOR]

Steganography is a technique for hiding secret messages while sending and receiving communications through a cover item. From ancient times to the present, the security of secret or vital information has always been a significant problem. The development of secure communication methods that keep recipient-only data transmissions secret has always been an area of interest. Therefore, several approaches, including steganography, have been developed by researchers over time to enable safe data transit. In this review, we have discussed image steganography based on Discrete Cosine Transform (DCT) algorithm, etc. We have also discussed image steganography based on multiple hashing algorithms like the Rivest–Shamir–Adleman (RSA) method, the Blowfish technique, and the hash-least significant bit (LSB) approach. In this review, a novel method of hiding information in images has been developed with minimal variance in image bits, making our method secure and effective. A cryptography mechanism was also used in this strategy. Before encoding the data and embedding it into a carry image, this review verifies that it has been encrypted. Usually, embedded text in photos conveys crucial signals about the content. This review employs hash table encryption on the message before hiding it within the picture to provide a more secure method of data transport. If the message is ever intercepted by a third party, there are several ways to stop this operation. A second level of security process implementation involves encrypting and decrypting steganography images using different hashing algorithms. [ABSTRACT FROM AUTHOR]

Social media blockchain is emerging as a promising solution to deal with privacy issues, by putting user privacy in edge nodes rather than centralized nodes. Under the protection of information encryption, only those who have cryptographic keys can get access to key information. This work aims at multimedia information in social media blockchain and utilizes the RSA encryption mechanism to construct the information encryption system. Due to the resilience of biometric features, the biometric cryptographic keys are not easy to be fabricated. Thus, this paper proposes a biometric keys-enhanced multimedia encryption algorithm for social media blockchain. First of all, the wiener filter is adopted to make some preprocessing operations to images, such as noise reduction. On this basis, the discrete wavelet transform is adopted to extract feature representation from images, and nonlinear approximation of contourlet transform is adopted to make feature fusion. Next, cryptographic keys can be generated from the fused biometric feature vectors to encrypt biometric data. Finally, some simulation experiments are conducted to evaluate performance of the proposal from three aspects: key generation time, security level and encryption-decryption time complexity. For key generation time, processing speed of the proposal is approximately 1–2 ms per sample. For security level, the proposal can reach an index value beyond 95% which is higher than comparison methods. For encryption-decryption time complexity, the proposal is about 30% lower than comparison methods. [ABSTRACT FROM AUTHOR]

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]

The exponential growth of Internet-of-Things (IoT) has raised several data security risks to the Fog–Cloud architecture. The performance and the computation cost of security algorithms hinder providing a secure real-time environment for IoT. This study proposes a novel two-layer cryptosystem, Cryptographic Harris Hawks Optimization (CryptoHHO), for Fog–Cloud architecture that reduces security overheads while maintaining confidentiality, integrity, and availability. The first layer of the proposed CryptoHHO is responsible for generating a highly randomized key using HHO to optimize Shannon entropy incorporation with transfer functions and a binarization mechanism. The second layer of CryptoHHO introduces a novel encipher model for encryption and decryption based on the Shift cipher, XOR operator, and an instance of crossover and mutation. The job execution avenue, i.e., Fog or cloud computing, is selected depending on the size of IoT requests, security sensitivity, and time sensitivity. The performance of CryptoHHO is compared against other emerging bio-inspired cryptographic algorithms. It was found that the CryptoHHO performs better than CryptoSSA, CryptoGWO, CryptoPSO, and CryptoWOA algorithms based on entropy, key generation time, transfer function comparison, execution time, and throughput. Further, the robustness of CryptoHHO is examined by various security analyses like brute-force attack resistivity, confusion-diffusion, CIA achievement, and statistical evaluations suggested by NIST and FIPS. [ABSTRACT FROM AUTHOR]

Recent rank-based attacks have reduced the security of Rainbow, which is one of the multi-layer UOV signatures, below the NIST security requirements by speeding up iterative kernel-finding operations using classical mathematics techniques. If quantum algorithms are applied to perform these iterative operations, the rank-based attacks may be more threatening to multi-layer UOV, including Rainbow. In this paper, we propose a quantum rectangular MinRank attack called the Q-rMinRank attack, the first quantum approach to key recovery attacks on multi-layer UOV signatures. Our attack is a general model applicable to multi-layer UOV signature schemes, and in this paper, we provide examples of its application to Rainbow and the Korean TTA standard, HiMQ. We design two quantum oracle circuits to find the kernel in consideration of the depth-width trade-off of quantum circuits. One is to reduce the width of the quantum circuits using qubits as a minimum, and the other is to reduce the depth using parallelization instead of using a lot of qubits. By designing quantum circuits to find kernels with fewer quantum resources and complexity by adding mathematical techniques, we achieve quadratic speedup for the MinRank attack to recover the private keys of multi-layer UOV signatures. We also estimate quantum resources for the designed quantum circuits and analyze quantum complexity based on them. The width-optimized circuit recovers the private keys of Rainbow parameter set V with only 1089 logical qubits. The depth-optimized circuit recovers the private keys of Rainbow parameter set V with a quantum complexity of 2 174 , which is lower than the complexity of 2 221 recovering the secret key of AES-192, which provides the same security level as parameter set III. [ABSTRACT FROM AUTHOR]

Cloud computing is an on-demand virtual-based technology to develop, configure, and modify applications online through the internet. It enables the users to handle various operations such as storage, back-up, and recovery of data, data analysis, delivery of software applications, implementation of new services and applications, hosting websites and blogs, and streaming of audio and video files. Thereby, it provides us many benefits although it is backlashed due to problems related to cloud security like data leakage, data loss, cyber attacks, etc. To address the security concerns, researchers have developed a variety of authentication mechanisms. This means that the authentication procedure used in the suggested method is multi-levelled. As a result, a better QKD method is offered to strengthen cloud security against different types of security risks. Key generation for enhanced QKD is based on the ABE public key cryptography approach. Here, an approach named CPABE is used in improved QKD. The Improved QKD scored the reduced KCA attack ratings of 0.3193, this is superior to CMMLA (0.7915), CPABE (0.8916), AES (0.5277), Blowfish (0.6144), and ECC (0.4287), accordingly. Finally, this multi-level authentication using an improved QKD approach is analysed under various measures and validates the enhancement over the state-of-the-art models [ABSTRACT FROM AUTHOR]