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In Eurocrypt'96, the concept of Designated Verifier Signature was proposed. Such signatures can only be verified by a single designated verifier specified during signature creation. However, there exist situations in which the signer, as well as the designated verifier, should be equipped with the ability to check the validity of the signature. At the same time, either of them should be able to help third parties to verify the signature. This is achieved by Directed Signature Schemes. In this paper, we consider directed signatures in the certificateless cryptography setting and propose an efficient pairing-free certificateless directed signature (CLDS) scheme. Then, we prove that the proposed CLDS scheme meets the needed security requirements in the random oracle model and under the assumption of the hardness of discrete logarithm and Gap Diffie-Hellman problems. We also compare the proposed scheme with the related ones to indicate the overall superiority of the proposed CLDS scheme. [ABSTRACT FROM AUTHOR]

Elliptic curve cryptography is a widely deployed technology for securing digital communication. It is the basis of many cryptographic primitives such as key agreement protocols, digital signatures, and zero-knowledge proofs. Fast elliptic curve cryptography relies on heavily optimised modular arithmetic operations, which are often tailored to specific micro-architectures. In this article, we study and evaluate optimisations of the popular elliptic curve Curve25519 for ARM processors. We specifically target the ARM NEON single instruction, multiple data (SIMD) architecture, which is a popular architecture for modern smartphones. We introduce a novel representation for 128-bit NEON SIMD vectors, optimised for SIMD parallelisation, to accelerate elliptic curve operations significantly. Leveraging this representation, we implement an extended twisted Edwards curve Curve25519 back-end within the popular Rust library "curve25519-dalek". We extensively evaluate our implementation across multiple ARM devices using both cryptographic benchmarks and the benchmark suite available for the Signal protocol. Our findings demonstrate a substantial back-end speed-up of at least 20% for ARM NEON, along with a noteworthy speed improvement of at least 15% for benchmarked Signal functions. [ABSTRACT FROM AUTHOR]

In the field of post-quantum security, isogeny-based cryptography stands out for its ability to fight quantum attacks. One of the key operations in isogeny-based schemes is finite field multiplication, which plays a crucial role in cryptographic protocols such as key exchange and digital signatures. To ensure practical implementations of these schemes, efficient finite field multiplication is essential. In this research, a novel optimization approach, the Crossover-Boosted Water Cycle Algorithm (CB-WCA), to enhance the efficiency of finite field multiplication in isogeny-based cryptography is proposed. By using both the WCA and a crossover method inspired by genetic algorithms, the CB-WCA effectively explores solution areas, aiming for the best solutions. The formulation of the finite field multiplication optimization problem and an objective function that quantifies the efficiency of the multiplication process based on computational cost is presented and defined. The CB-WCA is then applied to find the optimal set of parameters for finite field multiplication algorithms. Extensive experimental evaluations are conducted, comparing the performance of the CB-WCA-optimized algorithms with traditional optimization methods and other metaheuristic algorithms. Through the findings, it is evident that the CB-WCA stands out for its ability to achieve faster execution times and decrease computational costs. Furthermore, the optimized finite field multiplication algorithms are integrated into isogeny-based cryptographic schemes and evaluate their impact on cryptographic protocol efficiency and security. Real-world implementations showcase the practical applicability of the optimized algorithms in hardware and software environments. To ensure the security of the optimized algorithms, rigorous cryptanalysis is performed to verify their resilience against potential attacks, ensuring they meet the highest standards of security. [ABSTRACT FROM AUTHOR]

Blockchain technology provides efficient and secure solutions to various online activities by utilizing a wide range of cryptographic tools. In this article, we survey the existing literature on post-quantum secure digital signatures that possess exotic advanced features and that are crucial cryptographic tools used in the blockchain ecosystem for (1) account management, (2) consensus efficiency, (3) empowering scriptless blockchain, and (4) privacy. The exotic signatures that we particularly focus on in this work are the following: multi-/aggregate, threshold, adaptor, blind, and ring signatures. Herein the term "exotic" refers to signatures with properties that are not just beyond the norm for signatures, e.g., unforgeability, but also imbue new forms of functionalities. Our treatment of such exotic signatures includes discussions on existing challenges and future research directions in the post-quantum space. We hope that this article will help to foster further research to make post-quantum cryptography more accessible so that blockchain systems can be made ready in advance of the approaching quantum threats. [ABSTRACT FROM AUTHOR]

As Mobile Communication and Internet Systems (MCIS) have rapidly developed, security issues related to MCIS have become increasingly important. Therefore, the development and research of security technologies for mobile communication and internet systems are actively being conducted. Hash-Based Signature (HBS) uses a hash function to construct a digital signature scheme, where its security is guaranteed by the collision resistance of the hash function used. To provide sufficient security in the post-quantum environment, the length of hash should be satisfied for the security requirement. Modern HBS can be classified into stateful and stateless schemes. Two representative stateful and stateless HBS are eXtended Merkle Signature Scheme(XMSS) and SPHINCS + , respectively. In this paper, we propose two HBS schemes: K-XMSS and K-SPHINCS + , which replace internal hash functions of XMSS and SPHINCS + with Korean cryptography algorithms. K-XMSS is a stateful signature, while K-SPHINCS + is its stateless counterpart. We showcase the reference implementation of K-XMSS and K-SPHINCS + employing Lightweight Secure Hash (LSH) and two hash functions based on block ciphers (i.e., CHAM and LEA) as the internal hash function. In addition, K-XMSS and K-SPHINCS + using Advanced Vector Extensions 2 (AVX2) have been provided, demonstrating that they can be optimized for better performance using advanced implementation techniques than previous approaches. [ABSTRACT FROM AUTHOR]

Information security is a fundamental and urgent issue in the digital transformation era. Cryptographic techniques and digital signatures have been applied to protect and authenticate relevant information. However, with the advent of quantum computers and quantum algorithms, classical cryptographic techniques have been in danger of collapsing because quantum computers can solve complex problems in polynomial time. Stemming from that risk, researchers worldwide have stepped up research on post-quantum algorithms to resist attack by quantum computers. In this review paper, we survey studies in recent years on post-quantum cryptography (PQC) and provide statistics on the number and content of publications, including a literature overview, detailed explanations of the most common methods so far, current implementation status, implementation comparisons, and discussion on future work. These studies focused on essential public cryptography techniques and digital signature schemes, and the US National Institute of Standards and Technology (NIST) launched a competition to select the best candidate for the expected standard. Recent studies have practically implemented the public key encryption/key encapsulation mechanism (PKE/KEM) and digital signature schemes on different hardware platforms and applied various optimization measures based on other criteria. Along with the increasing number of scientific publications, the recent trend of PQC research is increasingly evident and is the general trend in the cryptography industry. The movement opens up a promising avenue for researchers in public key cryptography and digital signatures, especially on algorithms selected by NIST. [ABSTRACT FROM AUTHOR]

Multivariate cryptography is listed among the promising candidates for post-quantum cryptography primitives. Its hard problem depends on the difficulty of solving m multivariate quadratic equations in n variables over a finite field, hence the name Multivariate Quadratic Problem (MQP). In this paper, we present three multivariate digital signature forgery mechanisms by a rogue service provider. We also lay out techniques to identify two of such mechanisms. As for a potential signature forgery mechanism via Greatest Common Divisors of evaluated polynomials in the system, it is still an open question on how to detect it. This third strategy seems to inherit the NP-hard difficulties of a random MQP in totality. [ABSTRACT FROM AUTHOR]

Digital signature technology is essential for ensuring the authenticity and unforgeability of transactions in a private blockchain framework. In some scenarios, transactions require verification from multiple parties, each of whom needs to authenticate different parts of the transaction. To address this issue, researchers have developed multi-party ECDSA (Elliptic Curve Digital Signature Algorithm) signature schemes. However, these schemes either need to consider the authentication of different parts of the transaction or generate an aggregated signature. This paper proposes a novel solution that combines functional signatures and multi-party ECDSA signatures to create a multi-party functional signature for private blockchains. Compared to previous constructions, the proposed scheme ensures that each part of the transaction is verified. Furthermore, when the aggregate signature of the entire transaction cannot be verified, this scheme identifies the specific part of the transaction for which the signature authentication fails instead of rejecting the entire transaction. This paper uses a smart contract to securely deploy the proposed scheme and authenticate the f in functional signatures. The constructed scheme also provides security under the existential unforgeability of the ECDSA signature, even if n − 1 parties are corrupted, assuming a total of n parties. The scheme of this paper successfully conducted experiments on a personal computer, with three users taking approximately 343 ms, six users taking 552 ms, and nine users taking 791 ms. [ABSTRACT FROM AUTHOR]

Proxy signature is one of the important primitives of public-key cryptography and plays an essential role in delivering security services in modern communications. However, existing post quantum proxy signature schemes with larger signature sizes might not be fully practical for some resource-constrained devices (e.g., Internet of Things devices). A signature scheme with message recovery has the characteristic that part or all of the message is embedded in the signature, which can reduce the size of the signature. In this paper, we present a new identity-based proxy signature scheme over an NTRU lattice with message recovery (IB-PSSMR), which is more efficient than the other existing identity-based proxy signature schemes in terms of the size of the signature and the cost of energy. We prove that our scheme is secure under a Short Integer Solution (SIS) assumption that is as hard as approximating several worst-case lattice problems in the random oracle model. We also discussed some application scenarios of IB-PSSMR in blockchain and Internet of Things (IOT). This paper provides a new idea for the design of lattice signature schemes in low resource constrained environments. [ABSTRACT FROM AUTHOR]

According to the standard paradigm, white box cryptographic primitives are used to block black box attacks and protect sensitive information. This is performed to safeguard the protected information and keys against black box assaults. An adversary in such a setting is aware of the method and can analyze many system inputs and outputs, but is blind to the specifics of how a critical instantiation primitive is implemented. This is the focus of white-box solutions, which are designed to withstand attacks that come from the execution environment. This is significant because an attacker may obtain unrestricted access to the program's execution in this environment. The purpose of this article is to assess the efficiency of white-box implementations in terms of security. Our contribution is twofold: first, we explore the practical implementations of white-box approaches, and second, we analyze the theoretical foundations upon which these implementations are built. First, a research proposal is crafted that details white-box applications of DES and AES encryption algorithms. To begin, this preparation is necessary. The research effort planned for this project also includes cryptanalysis of these techniques. Once the general cryptanalysis results have been examined, the white-box design approaches will be covered. We have decided to launch an investigation into creating a theoretical model for white box, since no prior formal definitions have been offered, and suggested implementations have not been accompanied by any assurance of security. This is due to the fact that no formal definition of "white box" has ever been provided. In this way lies the explanation for why this is the situation. We define WBC to encompass the security requirements of WBC specified over a white box cryptography technology and a security concept by studying formal models of obfuscation and shown security. This definition is the product of extensive investigation. This state-of-the-art theoretical model provides a setting in which to investigate the security of white-box implementations, leading to a wide range of positive and negative conclusions. As a result, this paper includes the results of a Digital Signature Algorithm (DSA) study which may be put to use in the real world with signature verification. Possible future applications of White Box Cryptography (WBC) research findings are discussed in light of these purposes and areas of investigation. [ABSTRACT FROM AUTHOR]

Efficient lattice-based cryptosystems operate with polynomial rings with the Number Theoretic Transform (NTT) to reduce the computational complexity of polynomial multiplication. NTT has therefore become a major arithmetic component (thus computational bottleneck) in various cryptographic constructions like hash functions, key-encapsulation mechanisms, digital signatures, and homomorphic encryption. Although there exist several hardware designs in prior work for NTT, they all are isolated design instances fixed for specific NTT parameters or parallelization level. This article provides an extensive study of flexible design methods for NTT implementation. To that end, we evaluate three cases: (1) parametric hardware design, (2) high-level synthesis (HLS) design approach, and (3) design for software implementation compiled on soft-core processors, where all are targeted on reconfigurable hardware devices. We evaluate the designs that implement multiple NTT parameters and/or processing elements, demonstrate the design details for each case, and provide a fair comparison with each other and prior work. On a Xilinx Virtex-7 FPGA, compared to HLS and processor-based methods, the results show that the parametric hardware design is on average $4.4\times$ 4. 4 × and $73.9\times$ 73. 9 × smaller and $22.5\times$ 22. 5 × and $19.3\times$ 19. 3 × faster, respectively. Surprisingly, HLS tools can yield less efficient solutions than processor-based approaches in some cases. [ABSTRACT FROM AUTHOR]

In recent years, the Internet of Things (IoT) has attracted more attention after the integration of IoT devices with the cloud for data management. IoT is used for sharing data in healthcare services. However, security and privacy vulnerabilities still exist in data transfers to and from cloud environments. Due to memory limitations, it is difficult to implement security protocols in IoT devices. So an intermediate secure node is established to enhance data security and privacy while handling healthcare data. Blockchain is a renowned technology that is adopted in various data management and security applications, but its potential is not unleashed effectively in healthcare data management. Therefore in this research work, firstly, the data is pre-processed and then the Ant colony optimization method is used to find the shortest path for efficient data delivery. And, a blockchain based data security approach for healthcare data management is presented. The main objective is to enhance security against healthcare data threats. In the IoTs fog layer, a public-permissioned blockchain security process with elliptical curve cryptography and digital signature is presented as a distributed ledger database that provides immutable security, transparency in transactions, and prevents data tampering. The performance of the proposed approach is verified through various parameters like certificate generation time and size, data retrieval time, and size for better validation. [ABSTRACT FROM AUTHOR]

Blockchain-based platforms utilise cryptographic protocols to enforce the correct behaviour of users, as well as to guarantee a sufficient level of protection against malicious adversaries. Cryptography is, however, an ever-evolving discipline, and any breakthrough would have immediate consequences on the security of blockchain-based applications. A possible threat currently under investigation is given by the development of quantum computers, since several wide-adopted cryptographic protocols have been proved to be unsafe against quantum-capable adversaries. In this work, we propose a novel approach for the management of cryptographic primitives in smart-contract-based ledgers, discussing how it fits in both a (partially) permissioned and a fully permissionless setting. The cryptographic protocols are managed in a flexible manner via a set of smart-contracts defined on the ledger itself, in this way the choice of algorithms and parameters can change quickly. Among the advantages of this approach, we remark how it allows designing an adaptive post-quantum-based blockchain that keeps up with ongoing technological advances. In general, the introduction of new features and the application of fixes to a blockchain cause forks in the chain, which may cause major disruptions. The use of smart contracts in blockchain management allows to avoid this problem, dynamically introducing new protocols or deprecating old ones without compromising previous data. The Cryptographic Kernel approach has been adopted by Quadrans, an open-source, public, decentralised smart-contract-based blockchain with a specific focus on the needs of industry, complex supply chains, and IOT devices. [ABSTRACT FROM AUTHOR]

The RSA (Rivest–Shamir–Adleman) asymmetric-key cryptosystem is widely used for encryptions and digital signatures. Let (n , e) be the RSA public key and d be the corresponding private key (or private exponent). One of the attacks on RSA is to find the private key d using continued fractions when d is small. In this paper, we present a new technique to improve a small private exponent attack on RSA using continued fractions and multicore systems. The idea of the proposed technique is to find an interval that contains ϕ (n) , and then propose a method to generate different points in the interval that can be used by continued fraction and multicore systems to recover the private key, where ϕ is Euler's totient function. The practical results of three small private exponent attacks on RSA show that we extended the previous bound of the private key that is discovered by continued fractions. When n is 1024 bits, we used 20 cores to extend the bound of d by 0.016 for de Weger, Maitra-Sarkar, and Nassr et al. attacks in average times 7.67 h, 2.7 h, and 44 min, respectively. [ABSTRACT FROM AUTHOR]

With the rapid development of communication technology, the optimization of communication protocol, as a new generation of intelligent traffic system technology, has attracted more and more attention, in particular, the communication technology in traffic. In the authentication protocol of this paper, the symmetric cipher algorithm ZUC and the asymmetric cryptographic algorithm RSA are used as the cryptographic algorithms of the protocol. RSA is used to decrypt digital signatures for messages. In the current communication scheme, node communication does not have scalability and communication requirements in different scenarios, and a population key negotiation communication protocol was proposed in this paper. Employing the kana and random key parameters of the nodes in the roadside cell group, 3 communication protocols for group broadcasting, group to vehicle communication, and RSU communication between groups were designed. The results show that the protocol can meet the security requirements of network communication. The results show that the communication protocol in this paper is safe and reliable. At last, the communication efficiency of communication protocol is analyzed using communication overhead and average delay. The proposed protocol is an efficient communication protocol and the scheme is superior to other schemes in terms of communication overhead and average delay. [ABSTRACT FROM AUTHOR]

This paper proposes a discrete Gaussian sampling hardware design that can flexibly support different sampling parameters, that is more efficient (in area-delay product) compared to the majority of earlier proposals, and that has constant execution time. The proposed design implements a Cumulative Distribution Table (CDT) approach, reduces the table size with Gaussian convolutions, and adopts an innovative fusion tree search algorithm to achieve a compact and fast sampling technique—to our best knowledge, this is the first hardware implementation of fusion tree search algorithm. The proposed hardware can support all the discrete Gaussian distributions used in post-quantum digital signatures and key encapsulation algorithms (FALCON, qTESLA, and FrodoKEM), the homomorphic encryption library of SEAL, and other algorithms such BLISS digital signature and LP public-key encryption. Our proposed hardware can be configured at design-time to optimize a single configuration or at run-time to support multiple Gaussian distribution parameters. Our design, furthermore, has constant-time behavior by design, eliminating timing side-channel attacks—this is achieved by reading all table contents at the same time to also reduce the latency. The results on a Xilinx Virtex-7 FPGA show that our solution can outperform all prior proposals in area-delay product by 1.67–235.88×, only falling short to those designed for the LP encryption scheme. [ABSTRACT FROM AUTHOR]

Based on the quantum public-key cryptosystem, a transferable quantum cheque scheme is proposed. In our scheme, the bank is a trusted third party who acts as a key generation center and issues quantum blank cheque. The payer makes a payment to the payee by signing the quantum cheque with the private key, and the payee can verify the cheque with the payer's public key locally. The cheque can be transferred many times between different customers. The transfer and verification phases do not require the help of the bank. Hence, the cheque needs to be cleared only once, which reduces the workload on the bank. Security analysis results show that the proposed quantum cheque scheme is impossible to forge, double spend and repudiate. [ABSTRACT FROM AUTHOR]

In cryptography, elliptic curve cryptography (ECC) is considered an efficient and secure method to implement digital signature algorithms (DSAs). ECC plays an essential role in many security applications, such as transport layer security (TLS), internet protocol security (IPsec), and wireless sensor networks (WSNs). The proposed designs of ECC hardware implementation only focus on a single ECC variant and use many resources. These proposals cannot be used for resourceconstrained applications or for the devices that need to provide multiple levels of security. This work provides a multi-functional elliptic curve digital signature algorithm (ECDSA) and Edwardscurve digital signature algorithm (EdDSA) hardware implementation. The core can run multiple ECDSA/EdDSA algorithms in a single design. The design consumes fewer resources than the other single-functional design, and is not based on digital signal processors (DSP). The experiments show that the proposed core could run up to 112.2 megahertz with Virtex-7 devices while consuming only 10,259 slices in total. [ABSTRACT FROM AUTHOR]

Batch verification for digital signature scheme is a method to verify multiple signatures simultaneously. The complex exponent test (CE test for short) proposed by Cheon and Lee is one of the most efficient batch verification tests for several digital signature schemes on certain types of elliptic curves (including Koblitz curves). The security of the CE test relies essentially on the cardinality of a subset of a residue ring of the endomorphism ring of an elliptic curve over an ideal. They have evaluated the cardinality of the above subset, and have illustrated the effectiveness of the CE test by using the evaluation. The aim of this paper is to point out that their evaluation contains a flaw. The flaw is generally related to two roots of a quadratic equation which is used in their argument. We mend the flaw of their evaluation. Our correct evaluation shows that the CE test can achieve the same security as the underlying signature scheme on Koblitz curves. As a result, the CE test is a secure batch verification when the underlying signature scheme uses Koblitz curves. [ABSTRACT FROM AUTHOR]

A digital signature is one of the most widely used cryptographic primitives in asymmetry cryptography. According to the security requirements in different symmetry or asymmetry network models, various digital signatures have been developed in the literature. To protect the right of the signer, Chaum and Antrepen first introduced the concept of an undeniable signature, where interactive protocols are needed for the verification process. Besides, a signer can, also, perform a disavowal protocol to prove that they did not sign the message. On the other hand, threshold cryptography is, usually, used to protect the system from a single point of failure. In a (t , n) -threshold signature scheme, as long as t people in the group of n people participate, the signature can be smoothly signed. By combining these two features, an undeniable threshold signature enjoys the advantages from both sides. After our survey, we found that the existing undeniable threshold signature schemes are either insecure or apply impractical assumptions. Thus, in this manuscript, we aim at designing a novel and provably secure undeniable threshold signature scheme. The proposed scheme is formally proven to be unforgeable and invisible. Besides, our scheme supports cheater identification, which allows one to find the cheater, when a signing protocol fails. Moreover, the proposed scheme can be performed without the help of trusted third parties or secure cryptographic modules, which would be more practical when our scheme is deployed in real-world applications. [ABSTRACT FROM AUTHOR]

Currently, medical images represent basis of clinical diagnosis and source of telehealth and teleconsultation processes. Exchange of these images can be subject to several challenges, such as transmission bandwidth scarcity, time delivery, fraud, tampering, modifying, privacy, and more. This paper will introduce an algorithm consisting of a combination of compression and encryption techniques to meet such challenges in medical images field. First, compression is done by applying the Adaptive Arithmetic Coding (AAC) technique and controllable frequency quantization process in Discrete Wavelet Transform. After that, encryption process is applied using RSA and SHA-256 algorithms to encrypt the compressed file and to create digital signature. Performance analysis has shown that the algorithm can produce high compression ratio with good image quality, whereas range of PSNR near 45 dB and SIM is 0.88 as average values. For the security analysis, we have adopted data encryption and digital signature to guarantee the main data security services including integrity, authentication, and confidentiality, making the algorithm secure against passive or active attacks. [ABSTRACT FROM AUTHOR]

Sharing confidential voice-based messages over a public network or shared drive is quite challenging. There are some sensitive and highly confidential messages preferred to share through a voice message. The audio cryptography technique is the preferred way to transfer the content over a network. The proposed methodology multi-layer protection with deduplication (MLPD) enhance the security of voice messages by converting voice as an array of numeric values (Matrix) and applying multiple protection layers like (shuffling, transpose, and byte swap) and doing the reverse process in the receiver end with the help of the digital signature metadata file. Meanwhile, sharing the same message over a shared environment is another challenge. The encrypted redundant voice messages may flood the shared environment. The proposed model acknowledges the quality of encryption over voice data. The uniqueness of the proposed work is the performance of deduplication operation over the encrypted messages without any hashing techniques. The results show that MLPD outperforms advanced encryption standard and Fernet algorithms. [ABSTRACT FROM AUTHOR]

The paper deals with the development of novel blockchain technology for certificate management system using cognitive image steganography techniques, in the sense, a secured approach of managing educational certificates using the blockchain and digital image steganography, providing an edge over existing systems is dealt with in greater detail. The provision for educational and governmental certificate authentication falls under the broad category of digital certificate issuance, authentication, and verification. Issuing certificates in this category can be difficult and time-consuming. Currently, existing systems for certificate management cannot guarantee data security and system trust. Using blockchain can solve this problem. This research is aimed to enhance the document verification process using blockchain technology and identify the security themes required for document verification in the blockchain. For the first time a survey of this type has been done where Blockchain and image steganography have been combined together to develop a complete backend infrastructure and the frontend application for the certificate management portal. With the proposed method PSNR & MSR of average 59 dB & 0.55 could be achieved. Exhaustive literature survey w.r. t. the recent development in the blockchain technology is also provided. The simulation results presented in the simulation results section shows the efficiency of the methodology that has been developed in the block chain field & thus has got an edge over the works done by other researchers in this field. [ABSTRACT FROM AUTHOR]

Developing a solid e-voting system that offers fairness and privacy for users is a challenging objective. This paper is trying to address whether blockchain can be used to build an efficient e-voting system, also, this research has specified four blockchain technologies with their features and limitations. Many papers have been reviewed in a study covered ten years from 2011 to 2020. As a result of the study, the blockchain platform can be a successful public ledger to implement an e-voting system. Four blockchain technologies have been noticed from this study. These are blockchain using smart contracts, blockchain relying on Zcash platform, blockchain programmed from scratch, and blockchain depending on digital signature. Each blockchain model has details about its features and limitations. Finally, this study suggests developing a blockchain platform that can avoid limitations of currently used blockchain platforms by ensuring authentication, privacy, security for remote evoting processes. [ABSTRACT FROM AUTHOR]

Recently, a (t, n) threshold group signature scheme is present in Qin et al. (Quantum Inf Process 19(2):71, 2020). In this paper, we point out that it is not a threshold signature scheme, namely any number of members can generate a valid signature. By introducing a secret sharing scheme, we show how to improve the original scheme to a threshold signature scheme. In the original scheme, the key for the one-time pad encryption is used more than once, which makes the verifier recover the key and fabricate any signature at his will. We show how to close this security loophole. And we also show how to add a round for checking the honesty of the arbitrator, and thus the trust put on the arbitrator can be reduced. [ABSTRACT FROM AUTHOR]

Cooperative Intelligent Transportation Systems (C-ITS) improve driving experience and safety through secure Vehicular Ad-hoc NETworks (VANETs) that satisfy strict security and performance constraints. Relevant standards, such as the IEEE 1609.2, prescribe network-efficient cryptographic protocols to reduce communication latencies through a combination of the Elliptic Curve Qu-Vanstone (ECQV) implicit certificate scheme and the Elliptic Curve Digital Signature Algorithm (ECDSA). However, literature lacks open implementations and performance evaluations for vehicular systems. This paper assesses the applicability of IEEE 1609.2 and of ECQV and ECDSA schemes to C-ITSs. We release an open implementation of the standard ECQV scheme to benchmark its execution time on automotive-grade boards. Moreover, we evaluate its performance in real road and traffic scenarios and show that compliance with strict latency requirements defined for C-ITS requires computational resources that are not met by many automotive-grade embedded hardware platforms. As a final contribution, we propose and evaluate novel heuristics to reduce the number of signatures to be verified in real C-ITS scenarios. [ABSTRACT FROM AUTHOR]

The establishment of secure secret keys ahead of transmissions is one of the key issues in the field of information security. The security of traditional cryptographic secret key establishment mechanisms is seriously challenged by computing-intensive attacks, with the fast growth of high-performance computing. As an alternative, considerable efforts have been made to develop physical (PHY) layer security measures in recent years, such as link-signature-based (LSB) secret key extraction techniques. Those mechanisms have been believed secure, based on the fundamental assumption that wireless signals received at two locations are uncorrelated when separated by more than half a wavelength. However, this assumption does not hold in some circumstances under latest observations, rendering LSB key extraction mechanisms vulnerable to attacks. To address this problem, the formal theoretical analysis on channel correlations in both real indoor and outdoor environments is provided in this paper. Moreover, this paper proposes empirical statistical inference attacks (SIA) against LSB key extraction, whereby an adversary infers the signature of a target link. Consequently, the secret key extracted from that signature has been recovered by observing the surrounding links. In contrast to prior literature that assumes theoretical link-correlation models for the inference, our study does not make any assumption on link correlation. Instead, we employ machine learning (ML) methods for link inference based on empirically measured link signatures. We further propose a countermeasure against the SIAs, called forward-backward cooperative key extraction protocol with helpers (FBCH). In the FBCH, helpers (other trusted wireless nodes) are introduced to provide more randomness in the key extraction. Our experimental results have shown that the proposed inference methods are still quite effective even without making assumptions on link correlation. Furthermore, the effectiveness of the proposed FBCH protocol is validated by our experiment results. [ABSTRACT FROM AUTHOR]

Cryptographic hash functions are widely used primitives with a purpose to ensure the integrity of data. Hash functions are also utilized in conjunction with digital signatures to provide authentication and non-repudiation services. The SHA has been developed over time by the National Institute of Standards and Technology for security, optimal performance, and robustness. The best-known hash standards are SHA-1, SHA-2, and SHA-3. Security is the most notable criterion for evaluating the hash functions. However, the hardware performance of an algorithm serves as a tiebreaker among the contestants when all other parameters (security, software performance, and flexibility) have equal strength. Field Programmable Gateway Array (FPGA) is a reconfigurable hardware that supports a variety of design options, making it the best choice for implementing the hash standards. In this survey, particular attention is devoted to the FPGA optimization techniques for the three hash standards. The study covers several types of optimization techniques and their contributions to the performance of FPGAs. Moreover, the article highlights the strengths and weaknesses of each of the optimization methods and their influence on performance. We are optimistic that the study will be a useful resource encompassing the efforts carried out on the SHAs and FPGA optimization techniques in a consolidated form. [ABSTRACT FROM AUTHOR]

Blind signcryption is used to maintain the anonymity and privacy of the sender from other participants in an unsecured public network. It has vast applications for privacy related mechanisms such as electronic voting and electronic auction systems. Various blind signcryption schemes were introduced in the last two decades, depending upon the computational cost and the level of security. Some of these schemes were proven to be insecure and need further improvement. We analyzed a recently proposed blind signcryption scheme for multiple digital documents based on a hyperelliptic curve. Our cryptanalysis shows that the proposed blind signcryption scheme is not secure against the existing attacks. An adversary, with the knowledge of public parameters, can modify the signcrypted text of his choice. The successful cryptanalysis shows that the proposed scheme is unable to provide the security attributes of authentication and message integrity. To overcome the security flaws, we propose a modified version of this scheme. [ABSTRACT FROM AUTHOR]

The security of quantum cryptography is based on microscopic quantum properties, which is much higher than that of classical cryptography. In this paper, we combine the proxy threshold multiple signature with quantum signature in classical cryptography, which not only retains the agent property, threshold property, multiplicity and forward property of the original scheme, but also makes the scheme have the security of quantum signature. So it is a secure and practical signature scheme. [ABSTRACT FROM AUTHOR]

This article proposes options of electronic digital signature algorithms, the cryptographic strength of which is based on the complexity of computing a discrete logarithm in a finite field and the complexity of solving a problem of decomposing a sufficiently large odd number to prime factors, on the hash function used, as well as their cryptanalysis. Unlike existing electronic digital signature algorithms (RSA, El-Gamal) in the proposed new electronic digital signature algorithm signature generation process – s, is carried out using a private parameter - ϕ(N). [ABSTRACT FROM AUTHOR]

In 2003, Fischlin introduced the concept of progressive verification in cryptography to relate the error probability of a cryptographic verification procedure to its running time. It ensures that the verifier confidence in the validity of a verification procedure grows with the work it invests in the computation. Le, Kelkar and Kate recently revisited this approach for digital signatures and proposed a similar framework under the name of flexible signatures. We propose efficient probabilistic verification procedures for popular signature schemes in which the error probability of a verifier decreases exponentially with the verifier running time. We propose theoretical schemes for the RSA and ECDSA signatures based on some elegant idea proposed by Bernstein in 2000 and some additional tricks. We also present a general practical method, that makes use of efficient error-correcting codes, for signature schemes for which verification involves a matrix/vector multiplication. [ABSTRACT FROM AUTHOR]

Ensuring Quality of Service (QoS) and providing seamless connectivity are challenging in a mobile adhoc network. When Mobile Subscriber Station (MSS) moves between Access Service Network (ASNs), the authentication delay incurred during inter-ASN handover becomes a bottleneck. Pre-authentication of the MSSs at the target ASN (tASN) reduces the handover delay. Some existing pre-authentication schemes are prone to attacks. Modified EAP based Pre-authentication scheme using Improved ElGamal (MEPIE) proposed in this paper, modifies the existing Enhanced EAP based pre-Authentication scheme by using improved ElGamal digital signature and ElGamal encryption algorithm. To overcome the Denial of Service (DoS) and the replay attacks, MEPIE enhances ElGamal by using additional random variables. It outperforms the existing schemes in terms of Throughput, Packet Delivery Ratio (PDR), authentication delay, number of keys and Packet Loss Ratio (PLR) with negligible computation overhead. [ABSTRACT FROM AUTHOR]

We solve an open question in code-based cryptography by introducing two provably secure group signature schemes from code-based assumptions. Our basic scheme satisfies the CPA-anonymity and traceability requirements in the random oracle model, assuming the hardness of the McEliece problem, the Learning Parity with Noise problem, and a variant of the Syndrome Decoding problem. The construction produces smaller key and signature sizes than the previous group signature schemes from lattices, as long as the cardinality of the underlying group does not exceed 224, which is roughly comparable to the current population of the Netherlands. We develop the basic scheme further to achieve the strongest anonymity notion, i.e., CCA-anonymity, with a small overhead in terms of efficiency. The feasibility of two proposed schemes is supported by implementation results. Our two schemes are the first in their respective classes of provably secure groups signature schemes. Additionally, the techniques introduced in this work might be of independent interest. These are a new verifiable encryption protocol for the randomized McEliece encryption and a novel approach to design formal security reductions from the Syndrome Decoding problem. [ABSTRACT FROM AUTHOR]

Post-quantum (or quantum-resistant) cryptography refers to a set of cryptographic algorithms that are thought to remain secure even in the world of quantum computers. These algorithms are usually considered to be inefficient because of their big keys, or their running time. However, if quantum computers became a reality, security professionals will not have any other choice, but to use these algorithms. Lamport signature is a hash based one-time digital signature algorithm that is thought to be quantum-resistant. In this paper we will describe some simulation results related to the efficiency of the Lamport signature. [ABSTRACT FROM AUTHOR]

Multi-proxy signature schemes (MPSS) allow n proxy signers to generate a valid signature on behalf of the original signer. A new efficient self-certified MPSS with message recovery based on the Elliptic Curve Discrete Logarithm Problem (i.e., ECDLP) is proposed in this paper. A rationale for proposing a new scheme is to improve the verification process performance by combining the verification process with message recovery in one single stage (i.e., simultaneously). The security and performance analysis shows, the new scheme has many advantages over the traditional MPS schemes. These benefits include decreasing costs (i.e., certificate sizes, consumption time, and bandwidth requirements) and increasing speed. [ABSTRACT FROM AUTHOR]

Vehicular Ad hoc Networks (VANETs) are used to improve traffic management and reduce the number of road accidents by providing safety applications. However, VANETs are susceptible to a number of security attacks from malicious entities. To secure the network against these attacks, most of the researchers have proposed various security schemes based on cryptography and trust management. While both cryptography and trust management are effective to some extent, each scheme has some flaw to fully secure the network. In this paper, we propose a trust management scheme based on hybrid cryptography (TMHC) to secure VANET to a larger extent. As authentication is an integral part of trust establishment and secure communications between vehicles, the proposed TMHC integrates hybrid cryptography based authentication for efficient and robust trust management scheme. The hybrid cryptography includes, asymmetric identity-based (ID-based) digital signature and symmetric hash message authentication code (HMAC). The trusted road-side unit (RSU) evaluates trust-value, whereas, agent trusted authority (ATA) computes trust-value of vehicle based on its reward-points. The results are gained with extensive simulations to validate the proposed scheme. The results show that the proposed scheme meets security requirements and performs effectively. The communication overhead, computation overhead, storage overhead, and end-to-end delay of the proposed scheme were improved by 6% to 15%, 9% to 23%, 7% to 19%, and 4% to 15.85%, respectively, as compared to existing schemes. [ABSTRACT FROM AUTHOR]

It is regarded as a difficult task to design a secure MPKC fundamental schemes such as an encryption scheme. In this paper we introduce a new central trapdoor for multivariate quadratic (MQ) public-key cryptosystems that allows for encryption, in contrast to time-tested MQ primitives such as Unbalanced Oil and Vinegar or Rainbow which only allow for signatures. The same as UOV or Rainbow, our construction is single field scheme where the central polynomial system is chosen to have a particular structure that enables efficient inversion. After applying this transformation, the plaintext can be recovered by solving a linear system. Our new central trapdoor can use to replace the broken extension field calculation trapdoor and simple matrix encryption trapdoor, thereafter, we use the minus and plus modifiers to inoculate our scheme against known attacks. It is highlight that our encryption scheme is a good explore in the area of multivariate cryptography. Finally, a straightforward Magma implementation confirms the efficient operation of the public key algorithms. [ABSTRACT FROM AUTHOR]

A paper by Karati and Sarkar at Asiacrypt'17 has pointed out the potential for Kummer lines in genus 1, by observing that their SIMD-friendly arithmetic is competitive with the status quo. A more recent preprint explores the connection with (twisted) Edwards curves. In this article, we extend this work and significantly simplify the treatment of Karati and Sarkar. We show that their Kummer line is the x-line of a Montgomery curve translated by a point of order two, and exhibit a natural isomorphism to the y-line of a twisted Edwards curve. Moreover, we show that the Kummer line presented by Gaudry and Lubicz can be obtained via the action of a point of order two on the y-line of an Edwards curve. The maps connecting these curves and lines are all very simple. As a result, a cryptographic implementation can use the arithmetic that is optimal for its instruction set at negligible cost. [ABSTRACT FROM AUTHOR]

With rapid development of quantum computing technology in recent years, the cryptanalytic algorithms based on quantum characteristics can be realized in the near future. Therefore, the security of the traditional symmetric or asymmetric cryptography may not be guaranteed as in the past, especially the key-distribution protocols and cryptosystems which are either based on the hard problems of calculating discrete logarithm or factoring. The purpose of this article is to explain how the Grover and Shor algorithms threat the security of the modern cryptography. Meanwhile, the strategy to enhance the security of the symmetric cryptography under the threat of Grover algorithm is also provided. Moreover, the development of the quantum key distribution (QKD) and the post-quantum cryptography (PQC), which will be used to replace the traditional key distribution techniques in the future, is also described. Related suggestions to deal with the threats of the quantum computing are also provided in this article for the references of the network security-related departments to establish the corresponding strategies. [ABSTRACT FROM AUTHOR]

The advent of quantum computing threatens to break many classical cryptographic schemes, leading to innovations in public key cryptography that focus on post-quantum cryptography primitives and protocols resistant to quantum computing threats. Lattice-based cryptography is a promising post-quantum cryptography family, both in terms of foundational properties as well as in its application to both traditional and emerging security problems such as encryption, digital signature, key exchange, and homomorphic encryption. While such techniques provide guarantees, in theory, their realization on contemporary computing platforms requires careful design choices and tradeoffs to manage both the diversity of computing platforms (e.g., high-performance to resource constrained), as well as the agility for deployment in the face of emerging and changing standards. In this work, we survey trends in lattice-based cryptographic schemes, some recent fundamental proposals for the use of lattices in computer security, challenges for their implementation in software and hardware, and emerging needs for their adoption. The survey means to be informative about the math to allow the reader to focus on the mechanics of the computation ultimately needed for mapping schemes on existing hardware or synthesizing part or all of a scheme on special-purpose har dware. [ABSTRACT FROM AUTHOR]

Information security is one of the main concerns today. Digital signature plays an important role to ensure authentication, non-integrity and non-repudiation on a message. Digital signature can be computed using RSA, DSA and elliptic curve cryptography. It can be simple signature in which hash of the message is encrypted with the private key of the sender. This private key and corresponding public keys are generated by CA, and public key are bind in the digital certificate. Another approach is Identity Based (ID) signature in which private keys are generated by PKG and public key is derived from the user's identity. This is also known as certificate less communication. In ID based signature, there is no need to transmit public key over unsecure channel. Public keys are efficiently derived from the receiver's identity information such as name, email address, network address, IP address and now aadhar number. Email address can be forged by unauthorized persons. Today aadhar number is used as unique identity proof that can be used as ID to derive public key of the user. In this paper we have used aadhar number to propose an efficient and secure identity based multiple signature schemes using RSA. Proposed scheme is secure against forgery and public key replacement attack. [ABSTRACT FROM AUTHOR]

Reusable intellectual property (IP) cores from signal processing and multimedia form an integral part of consumer electronics (CE) systems. However, owing to the value it represents, it needs protection against important threats, such as piracy and illegal claim of ownership. This paper presents a novel multi-level encoding and encrypted-hash-based digital signature for protection of complex reusable IP core used in CE systems. For the first time in the literature, a digital signature-based IP core protection is proposed for digital signal processing (DSP) kernels. The proposed methodology is capable of encoding a DSP kernel application, followed by creating a digest of the encoded application to finally form a digital signature using RSA, which is subsequently implanted into the same design during architectural synthesis. The proposed approach on DSP benchmarks is capable of achieving higher robustness in terms of lower probability of coincidence - indicating stronger proof of authorship. The proposed approach achieves stronger robustness (on average by ~24.8%) as well as requires lesser storage hardware (on average reduction of ~14%) compared to similar prior work. [ABSTRACT FROM AUTHOR]

The deniable authentication and designated verifier signature protocol can achieve the property of deniability by a transcript simulation algorithm, so two protocols are similar in the concepts and application scenarios. In this paper, we will avoid the research ideas of classical cryptography and research how to convert quantum deniable authentication protocol into quantum designated verifier signature in this universal case that the owner of the signature and the signer isn't the same user in quantum designated verifier signature scheme such as electronic ID cards and e-passports. A mode on converting quantum deniable authentication into quantum designated verifier signature is firstly proposed by introducing quantum signature with public verifiability, including the entities and the implementation process converting, and then a real quantum designated verifier signature scheme is proposed, which satisfies all security requirements of a designated verifier signature scheme and can withstand intercept-resend attack and impersonation attack and entangle-measure attack. [ABSTRACT FROM AUTHOR]

In this work, we first present a low-cost, anomaly-based semi-supervised approach, which is instrumental in detecting the presence of ongoing side-channel attacks at runtime. We are, in particular, concerned with attacks that are carried out by creating intentional contentions in shared resources with cryptographic applications using a "spy" process. At a very high level, the approach quantifies contentions in shared resources, associates these contentions with processes, such as with a victim process, and issues a warning at runtime whenever the contentions reach a "suspicious" level. We then adapt this approach to detect the presence of four different types of cache-based side-channel attacks, namely prime-and-probe attacks on advanced encryption standard (AES), flush-and-reload attacks on AES and elliptic curve digital signature algorithm with Montgomery ladder algorithm, and Flush + Flush attacks on AES. To this end, we vary the shared resources monitored, the level of granularity at which the contentions in these resources are quantified, and the way the suspicious levels of contentions are detected. We evaluate the proposed approach also in cross-virtual machine setups (when applicable). The results of our experiments support our basic hypothesis that spy processes, which leverage information leaked by cryptographic applications through some shared resources, ironically leak information by themselves through the same or related channels, which can be analyzed to detect the presence of ongoing attacks at runtime. [ABSTRACT FROM AUTHOR]

Certificate-based cryptography (CB-PKC) is an attractive public key setting, which re- duces the complexity of public key infrastructure in traditional public key settings and resolves the key escrow problem in ID-based public key settings. In the past, a large number of certificate-based signature and encryption schemes were proposed. Nevertheless, the security assumptions of these schemes are mainly relied on the difficulties of the discrete logarithm and factorization problems. Unfortunately, both problems will be resolved when quantum computers come true in the future. Public key cryptography from lattices is one of the important candidates for post-quantum cryptog- raphy. However, there is little work on certificate-based cryptography from lattices. In the paper, we propose a new and efficient certificate-based signature (CBS) scheme from lattices. Under the short integer solution (SIS) assumption from lattices, the proposed CBS scheme is shown to be existen- tial unforgeability against adaptive chosen message attacks. Performance comparisons are made to demonstrate that the proposed CBS scheme from lattices is better than the previous lattice-based CBS scheme in terms of private key size and signature size. [ABSTRACT FROM AUTHOR]