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Since the RSA public key cryptosystem was proposed, it has been widely used because of its strong security. Although the proposal of the Shor's algorithm offers hope for cracking RSA, it is debatable whether the algorithm can actually pose a threat in practice. From the perspective of the quantum circuit of the Shor's algorithm, we analyse the feasibility of cracking RSA with improved quantum circuits using an ion-trap quantum computer. We present an improved quantum circuit for the modular exponentiation of a constant, which is the most expensive operation in Shor's algorithm for integer factorization. Whereas previous studies mostly focused on minimizing the number of qubits or the depth of the circuit, we minimize the number of CNOTs, which greatly affects the time to run the algorithm on an ion-trap quantum computer. First, we give the implementation of the basic arithmetic with the lowest known number of CNOTs and the construction of an improved modular exponentiation of a constant by accumulating intermediate data and using a windowing technique. Then, we precisely estimate the number of improved quantum circuits needed to perform the Shor's algorithm for factoring an n -bit integer, which is 217 n 3 / log 2 n + 4 n 2 + n. We analyse the running time and feasibility of the Shor's algorithm on an ion-trap quantum computer according to the number of CNOTs. Finally, we discussed the lower bound of the number of CNOTs needed to implement the Shor's algorithm. [ABSTRACT FROM AUTHOR]

With the development of cloud services and the Internet of Things, the integration of heterogeneous systems is becoming increasingly complex. Identity management is important in the coordination of various systems, and public key infrastructure (PKI) is widely known as an identity management methods. In PKI, a certificate authority (CA) acts as a trust point to guarantee the identity of entities such as users, devices, and services. However, traditional CAs that delegate the operations to a specific organization are not always suitable for heterogeneous services, and a new methodology is required to enable multiple stakeholders to securely and cooperatively operate a CA. In this study, we introduce the concept of a consortium CA and propose a distributed public key certificate-issuing infrastructure that realizes a consortium CA. The proposed infrastructure enables multiple organizations to cooperatively operate a CA suitable for services involving multiple stakeholders. We identify four requirements for the cooperative operation of a consortium CA and design the proposed infrastructure with distributed ledger technology. Furthermore, we present the implementation of smart contracts with Hyperledger Fabric and prove that the proposed infrastructure satisfies the four requirements. Finally, we confirm that certificate issuance and verification are stable at approximately 4 and 3 ms, respectively. [ABSTRACT FROM AUTHOR]

With the widespread adoption of cloud storage, ensuring the integrity of outsourced data has become increasingly important. Various cloud storage auditing protocols based on public key cryptography have been proposed. However, all of them require complex cryptographic operations and incur significant storage and communication costs. To address the issues of significant storage overhead for data tags, high computational complexity of cryptographic algorithms, and limited efficiency of dynamic data algorithms in signature algorithm-based cloud storage outsourcing data integrity verification protocols, we propose a dynamic auditing protocol called AB-DPDP, which is based on algebra. Our protocol reduces the computational complexity of tag generation by utilizing basic algebraic operations instead of the traditional cryptographic method used in most current auditing protocols. To reduce storage overhead and protect private data, our protocol stores only tags, allowing for data to be restored through these tags, as opposed to storing both tags and data on the cloud server. To accommodate for more frequent and efficient data dynamics, we propose the dynamic index skip table data structure. Furthermore, the security of our proposed protocol is thoroughly proven based on the security definition of secure cloud storage. Finally, through theoretical analysis and experimental evaluation, we demonstrate the advantages of our scheme in terms of data privacy, storage overhead, communication overhead, computation overhead, and data dynamic efficiency. [ABSTRACT FROM AUTHOR]

Homomorphic encryption technology is the holy grail of cryptography and has a wide range of applications in practice. This paper proposes a homomorphic encryption scheme over the fraction based on the Chinese remainder theorem (CRT) Dayan qiuyi rule. This homomorphic scheme performs encryption and decryption operations by forming congruence groups and has homomorphism. The solution in this paper first combines the traditional CRT algorithm with the Dayan qiuyi rule to obtain the CRTF algorithm that can be operated on the fraction field. Finally, in the decryption process, modulo arithmetic is used twice to obtain the correct plaintext components, restored to plaintext by CRTF. The scheme's security is related to a decisional version of an approximate GCD problem. The proof of theoretical derivation shows that this paper's homomorphic encryption scheme can realize the homomorphic addition operation in the fraction field. Compared with the CKKS scheme, efficiency is improved. [ABSTRACT FROM AUTHOR]

With the development of wireless technology, people increasingly rely on mobile devices. Since most mobile devices transmit sensitive information via insecure public channels, it is important to design multiauthentication key agreement protocols for security protection. Traditional scholars tend to use traditional public-key cryptosystems (PKCs) in their protocols to improve security. High-cost operations (e.g., elliptic curve point multiplication and bilinear pairing) were widely used in their scheme but were not suitable for mobile devices because of limited computing resources. In this study, we designed a novel high-efficiency multiauthentication and key agreement protocol and demonstrate its security in the random oracle model. Compared with other protocols, our proposed scheme only uses string concatenation operations, one-way hash functions, and XOR operations. In addition, our protocol requires much fewer computing resources to achieve the same level of security. [ABSTRACT FROM AUTHOR]

In order to enhance the cyber-security of networked control systems, Kogiso and Fujita (2015) proposed a concept of controller encryption using homomorphic encryption for the first time. Encrypted linear controllers using a homomorphic encryption scheme could conceal the information processed inside the controller device and maintain the original functions of controllers. In this paper, we propose a scheme to encrypt the linear controller using the BGN encryption, which supports homomorphic addition and multiplication. We also compare the efficiency of this scheme with the scheme with an encrypted controller using RSA encryption and Paillier encryption. [ABSTRACT FROM AUTHOR]

Edge computing, as an extension of cloud computing, outsources encrypted sensitive data to edge nodes to decrease latency and improve broadband efficiency. Although attribute-based keyword search (ABKS) can ensure the security of outsourced data and promote fine-grained access control of data, deficiencies still exist under the general ABKS scheme in the cloud, as follows: shared files owned by a single data owner, inflexible access control, key escrow problem, and high computational overhead. We propose an attribute-based multidata owner searchable encryption scheme in cloud-edge computing with effective policy update to address these problems. The two-level access control is used to realize the common management and fine-grained sharing of data by the multidata owner. All user keys are jointly generated by the central authority and attribute authority, and a key escrow is no longer required. Moreover, partial encryption and decryption calculations are shifted from resource-constrained data owners and users to edge nodes. Furthermore, our scheme not only supports policy update but also realizes the dynamic updating of the index. The security proof and performance analysis show that the scheme has strong security and practicality in the edge computing environment. [ABSTRACT FROM AUTHOR]

Identity-based proxy re-encryption (IB-PRE) converts the ciphertext encrypted under the delegator's identity to the one encrypted under the delegatee's identity through a semitrusted proxy without leaking delegator's private key and the underlying plaintext. At present, the security of most IB-PRE schemes relies on the hardness of the discrete logarithm solution or large integer decomposition and cannot resist attacks of the quantum algorithms. The majority of the IB-PRE schemes over lattice are secure only in the random oracle model. Aiming at such problems, the paper constructs a secure IB-PRE scheme over lattice in the standard model. In the scheme, the underlying encryption scheme proposed by Gentry et al. in EUROCRYPT 2010 is adopted to reduce the storage space of ciphertext. The proposed scheme is unidirectional collusion-resistant multihop and anonymous, and it is semantically secure against selective identity and chosen plaintext attack based on Decisional Learning With Errors with uniformly distributed errors (D-U-LWE) hard problem in the standard model. [ABSTRACT FROM AUTHOR]

The collection and sharing of electronic health records (EHRs) via the Internet of Things (IoT) can enhance the accuracy of disease diagnosis. However, it is challenging to guarantee the secure search of EHR during the sharing process. The advent of blockchain is a promising solution to address the issues, owing to its remarkable features such as immutability and anonymity. In this paper, we propose a novel blockchain-based secure sharing system over searchable encryption and hidden data structure via IoT devices. EHR ciphertexts of data owners are stored in the interplanetary file system (IPFS). A user with proper access permissions can search for the desired data with the data owner's time-bound authorization and verify the authenticity of the search result. After that, the data user can access the relevant EHR ciphertext from IPFS using a symmetric key. The scheme jointly uses searchable encryption and smart contract to realize secure search, time control, verifiable keyword search, fast search, and forward privacy in IoT scenarios. Performance analysis and proof demonstrate that the proposed protocol can satisfy the design goals. In addition, performance evaluation shows the high scalability and feasibility of the proposed scheme. [ABSTRACT FROM AUTHOR]

Space-based Internet of things (S-IoT) can provide global services and connection capabilities. It has broad emerging application, including marine monitoring, forest monitoring, animal monitoring, disaster emergency response and other fields. However, owing to the openness of satellite communications, S-IoT is vulnerable to hijacking attacks, and malicious attackers can tamper with or forge transmitted messages. More seriously, due to limited S-IoT node resources, it is difficult to directly apply existing security solutions to terrestrial networks to the S-IoT. In this study, we propose CSP, a novel, secure, and efficient scheme based on certificateless signatures and bilinear pairings for S-IoT. CSP consists of six phases: system setup, partial private key settings, private key settings, public key settings, signing and verifying. In CSP, we especially design that part of the private key comes from the ground KGC and the other part is generated by the communication entity itself. We theoretically prove CSP is secure, and it is able to resist tampering or forgery attacks. Moreover, it can also ensure the authenticity, integrity, unforgeability, and nonrepudiation of transmitted messages. We also conducted extensive experiments and compared CSP with the existing schemes. The experimental results demonstrate that CSP can significantly reduce the total scheme time consumption. Especially, it can reduce about 50–60% of the time in the signature verification phase. [ABSTRACT FROM AUTHOR]

In future, hundreds of years of mathematical problems that the security of public key cryptography algorithms rely on may be defeated by quantum algorithms. How can a digital signature scheme gracefully balance security and efficiency? This study uses the conjugate search problem and the left self-distributive system to combine and uses the RSA-like algorithm as the underlying structure to propose a new aggregated signature scheme. We, through the EUF game, under the random metaphor model, prove that the security of the scheme satisfies the adaptation unforgeability under selective message attack, the scheme can be finally reduced to the discrete logarithm problem or large prime number decomposition problem. In addition, we can achieve antiquantum attack and exhaustive attack by performing matrix calculations on the message, defining and changing the structure of the matrix by encoding, and setting thresholds for the matrix dimension and the length of the private key. In terms of efficiency, the message signature implementation is linear compared with the expansion rate in terms of storage and computing overhead, and the generation and verification of the final signature pair have nothing to do with the number of users. In addition, the length of the signature is fixed and the size is only the length of a single group, which effectively reduces the generation of public and private key pairs and saves a lot of storage space. The storage space and computational complexity are also effectively improved compared with other solutions. [ABSTRACT FROM AUTHOR]

Since the convenience and advancement of cloud applications, many users (e.g., companies or individuals) adopt remote cloud services to reduce the local storage overload and computing consumption. However, before transferring them to the cloud server, users always encrypt outsourced data for the privacy of important data, which deprives flexible usage of these data. Public key encryption with keyword search (PEKS) undoubtedly offers a precise resolution to this issue. Unfortunately, most PEKS schemes cannot fight against quantum computing attackers, which is increasingly a research hotspot. To achieve postquantum security and privacy-preserving search function, we propose a quantum-resistant PEKS scheme named IsoqurPEKS. Our proposed instantiation satisfies basic semantic security indistinguishable against chosen keyword attack (IND-CKA), and IsoqurPEKS is proved to be secure under the security model. Furthermore, we compare IsoqurPEKS with the other eight current PEKS schemes with respect to security properties, communication, and computation costs. The comparison results indicate that the proposed scheme has the best security and performance among the nine PEKS schemes. [ABSTRACT FROM AUTHOR]

Cloud computing can provide users with sufficient computing resources, storage, and bandwidth to meet their needs. Data security and privacy protection are among the new threats faced by users. Searchable encryption is the combination of search technology and encryption technology. Searchable encryption can upload the user's data to the cloud server after special encryption, and can realize the function of retrieving according to keywords. Comparatively to symmetric searchable encryption (SSE), public key searchable encryption (PEKS) simplifies key management greatly. However, most existing public key authenticated encryption with keyword search (PAEKS) schemes are based bilinear pairing, making them computationally expensive. Apart from this, complex retrieval requirements and the integrity of the results had not been considered. To address these problems, we propose a blockchain-based PAEKS schemes supporting multi-keyword queries and integrity verification. In addition, we provide security proofs for the PAEKS scheme under the decisional oracle Diffie-Hellman (DODH) assumption. This scheme a scheme that requires less storage and computational power than other schemes of the same kind. [ABSTRACT FROM AUTHOR]

Nowadays, the industrial Internet of Things (IIoT) is playing a promising role in the optimization of industrial systems. IIoT devices generate a great amount of data that could be used for different applications. Due to the untrusted nature of machine-to-machine (M2M) communication channels, data authenticity and integrity are an important issue that must be addressed. Especially, it is challenging to deal with the privacy disclosure that the heterogeneity of IIoT brings about. In this paper, we propose a privacy-preserving scheme for authenticity in heterogeneous IIoT systems. Our authentication schemes support many kinds of IIoT devices with multicryptographic configurations such as RSA-based, DL-based, ECC-based, and lattice-based cryptosystems. We provide the formalized proof of the unforgeability and privacy of the proposed schemes in the random oracle model. The experimental simulation demonstrates that the proposed schemes are feasible in the heterogeneous IIoT environment. [ABSTRACT FROM AUTHOR]

The Industrial Internet of Things (IIoT) improves productivity and intelligent manufacturing process through revolutionary technology. Due to the complexity of the manufacturing process, cross-domain access is inevitable. Recently, Meng et al. proposed a secure and efficient blockchain-assisted entity authentication mechanism BASA for IIoT cross-domain. In the BASA scheme, the authors utilized identity-based signature (IBS) to realize mutual authentication and the Ephemeral Elliptic Curve Diffie-Hellman (ECDHE) exchange mechanism to negotiate the session key. Due to the inherent key escrow problem of identity-based cryptography (IBC), the key generation center (KGC) can obtain the session key negotiated between two entities distributed in different domains. When KGC is threatened, the security of the session key is worrying. Considering this security concern, based on the BASA scheme, in this article, we first show a secure and efficient certificateless public-key signature (CL-PKS) scheme with anonymity. Then, combined with the ECDHE key exchange mechanism, we give an efficient cross-domain authentication and key agreement scheme CL-BASA with the aid of consortium blockchain. After that, we make security verification by the formal analysis tool, Tamarin, which shows that our CL-BASA is secure. The evaluation demonstrates that our CL-BASA may have a slight disadvantage in storage overhead, but it has obvious advantages than competitor schemes in terms of communication overhead and computational overhead. [ABSTRACT FROM AUTHOR]

The massive amounts of data collected by Internet of things (IoT) devices can be stored in clouds to solve the problem of the low storage capacity of IoT terminals. However, the privacy and security of outsourced IoT data may be compromised on the cloud side. Traditional cryptographic technologies can protect data privacy but require the user to retrieve the data for decryption and further processing, which would bring vast amounts of bandwidth and computation burden to users. This paper proposes a dual-server identity-based encryption scheme supporting authorized ciphertext equality test (DS-IBE-AET), where two noncolluding servers with authorizations from users can collaboratively carry out an equality test on outsourced IoT ciphertexts without decrypting the data. DS-IBE-AET can resist offline keyword guessing attacks confronted by existing encryption schemes with equality test in the single server model. Security analysis demonstrates that the proposed DS-IBE-AET scheme offers unforgeability for private keys of users and servers and confidentiality protection for outsourced IoT data and authentication tokens. The performance analysis indicates the practicality of our DS-IBE-AET construction for securing outsourced IoT data in clouds. [ABSTRACT FROM AUTHOR]

Aiming at the problem of illegal data sharing of malicious users in the access control scheme based on attribute-based encryption, an access control scheme that can restrict the sending ability of data owners is proposed. By adding a sanitizer to sanitize the ciphertext, it can ensure that parties who do not adhere to the system control policy cannot share information effectively. The scheme is constructed based on blockchain, and the traceability of access process can be realized. Off-chain storage can also lower the blockchain storage load. The scheme meets the No-Read and No-Write rules, achieves chosen-plaintext attack security under the random oracle model, and can against quantum attacks. As a result of theoretical analysis and experimental simulation, the scheme has certain feasibility and practical significance. [ABSTRACT FROM AUTHOR]

It is known that, given an RSA modulus, n = p q , the public key e and the corresponding private key d satisfy the modulo congruence e d ≡ 1 mod ϕ n , where ϕ n = p − 1 q − 1 . Usually, the private key d can be computed efficiently using the extended Euclidean algorithm, and it is common knowledge that the private key is unique in the sense of modular ϕ n . This paper shows that there exist multiple private keys d ; they all satisfy that d < ϕ n . This paper also presents the exact relationship between an RSA public key and a corresponding private key. [ABSTRACT FROM AUTHOR]

Because there is no multiplication of numbers in tropical algebra and the problem of solving the systems of polynomial equations in tropical algebra is NP-hard, in recent years some public key cryptography based on tropical semiring has been proposed. But most of them have some defects. This paper proposes new public key cryptosystems based on tropical matrices. The security of the cryptosystem relies on the difficulty of the problem of finding multiple exponentiations of tropical matrices given the product of the matrices powers when the subsemiring is hidden. This problem is a generalization of the discrete logarithm problem. But the problem generally cannot be reduced to discrete logarithm problem or hidden subgroup problem in polynomial time. Since the generating matrix of the used commutative subsemirings is hidden and the public key matrices are the product of more than two unknown matrices, the cryptosystems can resist KU attack and other known attacks. The cryptosystems based on multiple exponentiation problem can be considered as a potential postquantum cryptosystem. [ABSTRACT FROM AUTHOR]

Password-authenticated key exchange (PAKE) protocols play an important role in cryptography. Most of PAKEs are based on the Diffie–Hellman key exchange protocols or RSA encryption schemes, but their security is threatened by quantum computers. In this study, we propose the first code-based PAKE protocol based on Ouroboros, which is a code-based key exchange protocol. Our scheme enjoys high efficiency and provides mutual explicit authentication, with a security reduction to decoding random quasi-cyclic codes in the random oracle model. [ABSTRACT FROM AUTHOR]

Blockchain technology has been widely applied in numerous industries with its decentralization, verifiability, distributivity, and immutability. However, the identity privacy security of blockchain users is facing serious threats because of the openness of traditional blockchain transaction information. Moreover, numerous traditional cryptographic algorithms used by blockchain transaction networks are difficult to attack quantum computing. In this paper, we propose a new lattice-based blind ring signature scheme in allusion to completely anonymous blockchain transaction systems. There into, the blind ring signature can implement the complete anonymity of user identity privacy in blockchain transactions. Meanwhile, lattice cryptography can availably resist quantum computing attacks. Firstly, the proposed signature scheme has strong computational security based on the small integer solution (SIS) problem and a high sampling success rate by utilizing the techniques of rejection sampling from bimodal Gaussian distribution. Secondly, the proposed signature scheme can satisfy the correctness and security under the random oracle model, including anonymity, blindness, and one-more unforgeability. Thirdly, we construct a blockchain transaction system based on the proposed blind ring signature algorithm, which realizes the completely anonymous and antiquantum computing security of the blockchain users' identity privacy. Finally, the performance evaluation results show that our proposed blind ring signature scheme has lower latency, smaller key size, and signature size than other similar schemes. [ABSTRACT FROM AUTHOR]

Cloud storage technology is evolving at a high speed; effectively auditing the cloud data's integrity has become a focal point. Recently, Ming and Shi proposed a certificateless integrity auditing scheme with a privacy protection function. The scheme used the certificateless cryptosystem to solve the certificate management problem of the auditing schemes based on public key infrastructure and the key escrow problem of the identity-based auditing schemes. Although their scheme is novel and efficient, we found that their scheme was not secure and could not achieve integrity auditing of cloud data. The malicious cloud server can generate the proof through the blocks and tags sent by the user. On the basis of the original scheme, we propose an improved auditing scheme; our new scheme is more secure and effective. In addition, for the problem of idle tags in the existing cloud data integrity auditing scheme, we propose the idea of intermediate tags and we applied the idea to the improved scheme to improve audit efficiency. [ABSTRACT FROM AUTHOR]

Vehicular Ad Hoc Network (VANET) is a wireless Mobile Ad Hoc Network that is used for communication between vehicles, vehicles and fixed access points, and vehicles and pedestrians. However, because of the use of open wireless channels, VANET is more vulnerable. Therefore, VANET security is critical for safe driving and user privacy protection. Authentication and key agreement are crucial for ensuring security. Numerous authentication schemes have been proposed between vehicles and roadside units (RSUs). Many solutions are authentication and key negotiation between the vehicle and a single RSU. The vehicle passing through a region needs to complete authentication and key agreement with multiple RSUs separately, which brings a great burden to the vehicle. In order to simplify the authentication process of vehicles and multiple RSUs and improve the efficiency of authentication and key agreement, an efficient authentication and key agreement scheme based on RSU cache is proposed when the vehicle moves from one RSU to another RSU region. In the proposed scheme, RSUs are divided into regions, and each region has a RSU cluster head. When the vehicle enters a certain region and authenticates with a RSU successfully, the RSU submits the authentication information to the RSU cluster head. The RSU cluster head shares the authentication information with other RSUs in the region using the shared key. Other RSUs record the authentication information in the cache. When the vehicle communicates with other RSUs, the authentication is not necessary; the session key can be negotiated by simply exchanging information. After using the cache, the calculation and communication cost of the authentication and key negotiation between the vehicle and other RSU can be significantly saved, the calculation cost is reduced by 37%, and the traffic is reduced by 35%. The random oracle model is used to prove the security of the scheme. The results revealed that the authentication overhead of the proposed scheme is considerably lower than those of other schemes. Compared with the related schemes, the computational cost of the proposed scheme is reduced by 34% on average; the communication cost is close to other related schemes. Moreover, the security analysis shows that the proposed scheme provides better security compared to other related schemes. [ABSTRACT FROM AUTHOR]

With the development of blockchain, many studies apply blockchain to certificate revocation. However, existing blockchain-based certificate revocation schemes have two shortcomings. First, the storage overhead on the blockchain is relatively large. Second, as the number of revoked certificates increases, the misjudgment rate of certificate status will increase accordingly, so a public key infrastructure implementation certificate revocation scheme based on blockchain and accumulators, called CR-BA, is proposed. First, CR-BA expands the certificate structure, adding a revocation factor and a smart contract account for accessing the blockchain in the certificate extension, which is filled by the CA when the certificate is generated. Then, when the certificate is to be revoked, CA generates the revocation fingerprint through the revocation factor and publishes it to the blockchain. Finally, when the user needs to verify the status of the certificate, CA calculates the revocation fingerprint according to the revocation factor on the certificate, then compares it with the existing revocation fingerprint on the blockchain, and returns the comparison result to the user. The experimental results show that this scheme can effectively overcome the storage and misjudgment problems caused by existing blockchain-based certificate revocation schemes and improve the query efficiency of certificate revocation information. [ABSTRACT FROM AUTHOR]

The Signal Protocol is one of the most popular privacy protocols today for protecting Internet chats and supports end-to-end encryption. Nevertheless, despite its many advantages, the Signal Protocol is not resistant to Man-In-The-Middle (MITM) attacks because a malicious server can distribute the forged identity-based public keys during the user registration phase. To address this problem, we proposed the IBE-Signal scheme that replaced the Extended Triple Diffie–Hellman (X3DH) key agreement protocol with enhanced Identity-Based Encryption (IBE). Specifically, the adoption of verifiable parameter initialization ensures the authenticity of system parameters. At the same time, the Identity-Based Signature (IBS) enables our scheme to support mutual authentication. Moreover, we proposed a distributed key generation mechanism that served as a risk decentralization to mitigate IBE's key escrow problem. Besides, the proposed revocable IBE scheme is used for the revocation problem. Notably, the IND-ID-CPA security of the IBE-Signal scheme is proven under the random oracle model. Compared with the existing schemes, our scheme provided new security features of mutual authentication, perfect forward secrecy, post-compromise security, and key revocation. Experiments showed that the computational overhead is lower than that of other schemes when the Cloud Privacy Centers (CPCs) number is less than 8. [ABSTRACT FROM AUTHOR]

Password-authenticated key exchange (PAKE) protocols play an important role in cryptography. Most of PAKEs are based on the Diffie–Hellman key exchange protocols or RSA encryption schemes, but their security is threatened by quantum computers. In this study, we propose the first code-based PAKE protocol based on Ouroboros, which is a code-based key exchange protocol. Our scheme enjoys high efficiency and provides mutual explicit authentication, with a security reduction to decoding random quasi-cyclic codes in the random oracle model. [ABSTRACT FROM AUTHOR]

Identity-based encryption is an important cryptographic system that is employed to ensure confidentiality of a message in communication. This article presents a provably secure identity based encryption based on post quantum security assumption. The security of the proposed encryption is based on the hard problem, namely Learning with Errors on integer lattices. This construction is anonymous and produces pseudo random ciphers. Both public-key size and ciphertext-size have been reduced in the proposed encryption as compared to those for other relevant schemes without compromising the security. Next, we incorporate the constructed identity based encryption (IBE) for Internet of Things (IoT) applications, where the IoT smart devices send securely the sensing data to their nearby gateway nodes(s) with the help of IBE and the gateway node(s) secure aggregate the data from the smart devices by decrypting the messages using the proposed IBE decryption. Later, the gateway nodes will securely send the aggregated data to the cloud server(s) and the Big data analytics is performed on the authenticated data using the Artificial Intelligence (AI)/Machine Learning (ML) algorithms for accurate and better predictions. [ABSTRACT FROM AUTHOR]

Autonomous Vehicle Platoon (AVP) is the most anticipated application of 5G ultrareliable and low latency communications. By joining the preexisting platoon to form the real-time AVP (RAVP), individual vehicles could gain benefits such as fuel consumption reduction and traffic safety enhancement. Unlike the scheduled AVP which only contains fixed vehicles, members in RAVP change frequently since individual vehicles would want to join or leave the platoon any time. Besides, malicious vehicles may attempt to sneak into the RAVP and try to manipulate the platoon. Public key cryptography and access control mechanisms can be adopted to create a relatively isolated area for communication inside the platoon. Nevertheless, there exist few works that take into account the regulation of the dynamic change members in RAVP. In this paper, we propose a membership management scheme for 5G-enabled RAVP by integrating revocable attribute-based encryption (RABE) and blockchain, namely, GAP-MM. It realizes fine-grained access control of key distribution and malicious vehicle's key revocation efficiently. The sufficient evaluations and security analysis indicate that GAP-MM is practical for RAVP scenario in terms of both efficiency and security. [ABSTRACT FROM AUTHOR]

Cloud storage is a popular model of the application in various fields, and the security of storage data and access permission have been widely considered. Attribute-based encryption (ABE) provides fine-grained user access control and ensures data confidentiality. However, current ABE access control schemes rely on trusted cloud servers and provide a low level of security. To solve these problems of traditional encryption schemes, we propose a blockchain-based and ABE cloud storage data access control scheme. In this article, blockchain and smart contract technology are the core elements to ensure data integrity and build a decentralized verification method for outsourcing results. This application can minimize the reliance on servers in the cloud environment. Based on the ciphertext-policy ABE algorithm, the proposed scheme supports a hidden access policy to avoid the risk of privacy leakage. In addition, we adopt outsourcing technology and predetected decryption algorithms to reduce the computational overhead of local and outsourced servers. Security analysis and performance evaluation show that our proposed scheme has high computational efficiency and satisfies the condition of indistinguishability under the chosen-ciphertext attacks. [ABSTRACT FROM AUTHOR]

With the advancements in the new technologies like IoT, the healthcare sector is also growing rapidly. The core concept of introducing IoT in the healthcare centers is to make it remotely accessible, so that communication between doctor and patient can be easy, and diagnosis of any disease can be remotely done through the Internet in case of emergency. The major objective of this study is to develop a security framework for the healthcare industry that can encrypt secret data on cloud servers using block-based data encoding. Since any information that is available on the Internet is vulnerable to various attacks, and the medical records of the patients carry sensitive information that must not be accessible to any unauthorized or unauthentic person, in this context, the concept of Blockchain (BC) technology was introduced in the healthcare systems. In the past few years, a number of BC based healthcare models were proposed in the system; however, these systems are decentralized in nature, which is a feature of Blockchain technology, but in certain applications, especially in healthcare, this feature gave rise to a problem termed as disease overlapping when the count of chains gets increased. To solve this issue, a BC based framework is used in this work that has a feature of creating a separate block in the chain every time whenever any alteration in information about patient's health, any allergies, new symptoms, medications, etc. is updated. In addition to this, securing the sensitive information of patients is taken into consideration by developing an improved and enhanced multilayer Blockchain based IoT data security approach that not only protects the data, but also builds the trust between patients/user and healthcare service providers. The main focused area of this research article is to propose a security framework for healthcare domain that can encrypt the confidential data over cloud server under block-based data encoding. In the proposed approach, 128-bit AES key is generated in order to support the SHA-256 hashing algorithm. Individual user's data is subdivided to blocks and encrypted to secure it from unauthorized access. An interface-based system is designed to present the real-world usage of the proposed model in healthcare application. Finally, the effectiveness of the proposed approach is validated in the MATLAB software in terms of MAE, RMSE, MSE, encryption time, and decryption time. The RSA and DSA are the most trending encryption algorithms. These algorithms are crucial components of Blockchain technology, implemented in the proposed work, and later on, their performances are also compared with each other to check their effectiveness. The simulation results demonstrated that the proposed encrypting algorithm surpasses the other encryption approaches such as RSA and DSA in all factors to prove its supremacy. The experimental results show that the encryption and decryption time are lowest in the proposed framework; therefore, its performance is more effective and robust. It is also more effective and resilient. [ABSTRACT FROM AUTHOR]

Traditional searchable encryption schemes construct document vectors based on the term frequency-inverse document frequency (TF-IDF) model. Such vectors are not only high-dimensional and sparse but also ignore the semantic information of the documents. The Sentence Bidirectional Encoder Representations from Transformers (SBERT) model can be used to train vectors containing document semantic information to realize semantic-aware multi-keyword search. In this paper, we propose a privacy-preserving searchable encryption scheme based on the SBERT model. The SBERT model is used to train vectors containing the semantic information of documents, and these document vectors are then used as input to the Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN) clustering algorithm. The HDBSCAN algorithm generates a soft cluster membership vector for each document. We treat each cluster as a topic, and the vector represents the probability that the document belongs to each topic. According to the clustering process in the schemes, the topic-term frequency-inverse topic frequency (TTF-ITF) model is proposed to generate keyword topic vectors. Through the SBERT model, searchable encryption scheme can achieve more precise semantic-aware keyword search. At the same time, the special index tree is used to improve search efficiency. The experimental results on real datasets prove the effectiveness of our scheme. [ABSTRACT FROM AUTHOR]

Signcryption is the method of combining a digital signature with encryption in a single logical step to get the cryptographic primitives of a public key. However, in addition to signcryption, we sometimes require anonymity and delegation of rights. In this paper, we propose a scheme called proxy promised signcryption to address all of these objectives simultaneously. In this scheme, the actual sender or signer delegates authority to an agent known as signcrypter for signcryption of the actual ciphertext. The agent entity is facilitated to generate a promised signcrypted text. The signcrypted text is then communicated to the intended recipient. The proposed work aims to reduce computation and communication costs, which has been tested by comparing it to existing schemes. The results obtained from this comparison support the aims of our scheme. The proposed scheme's security has also been evaluated using the Automated Validation of Internet Security Protocols and Applications (AVISPA) tool. The results validate that our scheme resists well-known cyberattacks. [ABSTRACT FROM AUTHOR]

This study is aimed at the authentication problem between the node's public key and the node in the sensor network of the Internet of Things(IoT). As well as the sensor node key distribution needs to verify trusted nodes, resulting in a lot of storage and computational overhead problems. A routing-driven key management scheme for the IoT based on identification certificate authentication system is proposed. The scheme takes the identification key pair of the node as the verification key to verify the random key pair generated by the node to ensure that the whole process does not need the intervention of a trusted third party; random key pairs are generated by nodes independently to ensure that each sensor node has different keys. When a node is broken, it will not cause damage to other nodes. At the same time, the shared key is only established for adjacent sensor nodes that communicate with each other to ensure the security and lightweight storage overhead of the sensor nodes. The experimental analysis shows that the scheme can provide better security, can effectively reduce sensor nodes' storage space and energy consumption, and has higher advantages in safety and performance. [ABSTRACT FROM AUTHOR]

The development of the Internet of Things (IoT) has been facing severe security threats, and the security and fine-grained access control of data in the IoT is one of the security problems that urgently need to deal with. Attribute-based encryption (ABE) schemes over lattice can not only achieve fine-grained access control but also resist quantum attacks. However, most schemes are single-bit encryption, which is inefficient. In this study, a multibit inner product predicate encryption (PE) scheme over lattice is proposed, which effectively expands the plaintext space. The scheme can realize multibit attribute-based encryption with the hidden access structure for data security in the IoT and support And-gate operation in the access structure with multiattribute. The fine-grained access control of ciphertext data can be realized under the condition of ensuring data privacy. The security of the scheme is based on LWE problem, and it can resist quantum attacks, that is, CPA security under the standard model. [ABSTRACT FROM AUTHOR]

In order to solve the problem of multiuser security sharing and privacy protection of the speech data in cloud storage and realize efficient encrypted speech retrieval, an encrypted speech retrieval scheme based on multiuser searchable encryption was proposed. Firstly, the ciphertext-policy attribute-based encryption (CP-ABE) and searchable encryption (SE) are combined to support a multiuser searchable speech encryption scheme, which achieves the encryption and fine-grained access control of the speech data. Secondly, the Mel frequency cepstral coefficient (MFCC) feature of the original speech that is used as the input of the long- and short-term memory network (LSTM) is extracted to perform the deep semantic feature extraction as the speech keywords. Finally, the speech keywords are encrypted to generate a secure index, bound together with the encrypted speech, and then stored in the cloud. During the user retrieving, the keywords of query speech are extracted by utilizing the trained LSTM to generate the search trapdoor of the user and then uploaded to the cloud server, and the Euclidean distance is used for matching the security index with the search trapdoor. In addition, a proxy server is introduced to execute the partial ciphertext decryption operations to reduce computation overhead and storage space. The theoretical analysis and experimental results show that the proposed scheme has higher security and retrieval accuracy and can realize the secure storage of the massive speech data and multiuser data sharing. [ABSTRACT FROM AUTHOR]

In the current E-healthcare scenarios, medical institutions are used to encrypt the information and store it in an Electronic Health Record (EHR) system in order to ensure the privacy of medical information. To realize data sharing, a Public-key Encryption with Keyword Search (PEKS) scheme is indispensable, ensuring doctors search for medical information in the state of ciphertext. However, the traditional PEKS scheme cannot resist the keyword guessing quantum computing attacks, and its security depends on the confidentiality of the secret key. In addition, classical PEKS hand over the search process to a third party, affecting the search results' accuracy. Therefore, we proposed a postquantum Public-key Searchable Encryption scheme on Blockchain (PPSEB) for E-healthcare scenarios. Firstly, we utilized a lattice-based cryptographic primitive to ensure the security of the search process and achieve forward security to avoid key leakage of medical information. Secondly, we introduced blockchain technology to solve the problem of third-party untrustworthiness in the search process. Finally, through security analysis, we prove the correctness and forward security of the solution in the E-healthcare scenarios, and the comprehensive performance evaluation demonstrates the efficiency of our scheme compared with other existing schemes. [ABSTRACT FROM AUTHOR]

Gentry, Sahai, and Waters (CRYPTO 2013) proposed the notion of multi-identity fully homomorphic encryption (MIFHE), which allows homomorphic evaluation of data encrypted under multiple identities. Subsequently, Clear and McGoldrick (CANS 2014, CRYPTO 2015) proposed leveled MIFHE candidates. However, the proposed MIFHE is either based on i O , which is a nonstandard assumption or single hop; that is, an arbitrary "evaluated" ciphertext under a set of identities is difficult to further evaluate when new ciphertexts are encrypted under additional identities. To overcome these drawbacks, we propose a leveled multi-hop MIFHE scheme. In a multi-hop MIFHE scheme, one can evaluate a group of ciphertexts under a set of identities to obtain an "evaluated" ciphertext, which can be further evaluated with other ciphertexts encrypted under additional identities. We also show that the proposed MIFHE scheme is secure against selective identity and chosen-plaintext attacks (IND-sID-CPA) under the learning with errors (LWE) assumption. [ABSTRACT FROM AUTHOR]

Multiplication on polynomial rings has been widely used in public-key cryptographic schemes based on ideal lattices. It is an important module that significantly affects the efficiency of the schemes. Improved Preprocess-then-NTT (IPtNTT) is an algorithm which can fast realize multiplication on polynomial rings. Compared with the Number Theoretic Transform (NTT), the IPtNTT weakens the parameter restriction of lattice-based public-key cryptographic schemes. By optimizing the IPtNTT with the AVX2 instruction set, we reduce the clock cycles consumed by multiplication on polynomial rings to 15%–22%. According to the experimental results, we give specific suggestions on using AVX2 optimized IPtNTT to realize multiplication on polynomial rings with different parameters chosen in lattice-based public-key cryptosystems. [ABSTRACT FROM AUTHOR]

FOG-enabled cyber-physical systems (FOG-CPSs) open new security challenges as the local edge devices are easier to compromise than a traditional cloud server. Remote data integrity checking (RDIC) plays an important role in safeguarding against data corruption from a storage server. Certificateless cryptography (CLPKC)-based RDIC schemes do not suffer from the drawbacks of the public key infrastructure (PKI)-based RDIC protocols. Most of the CLPKC-based RDIC schemes proposed in the literature deal with personal data. However, in a FOG-CPS, it is also important to audit a data file shared by a group of edge devices. Most of the existing group shared data auditing schemes lack mechanisms to defend against a semi-trusted data auditor applicable for a FOG-CPS scenario. In order to address these issues, in this paper, we propose a novel CLPKC-based group shared data auditing protocol tailored to the specific security requirements of a FOG-CPS. Besides, we perform a detailed cryptanalysis of two existing CLPKC-based privacy-preserving group shared data auditing schemes. The formal security analysis of our proposed protocol establishes metadata and data integrity proof unforgeability and claimed zero-knowledge privacy and reliability properties through rigorous proofs in the random oracle model setting. Performance evaluations establish the efficiency of our proposed protocol. [ABSTRACT FROM AUTHOR]

Digital signatures are crucial network security technologies. However, in traditional public key signature schemes, the certificate management is complicated and the schemes are vulnerable to public key replacement attacks. In order to solve the problems, in this paper, we propose a self-certified signature scheme over lattice. Using the self-certified public key, our scheme allows a user to certify the public key without an extra certificate. It can reduce the communication overhead and computational cost of the signature scheme. Moreover, the lattice helps prevent quantum computing attacks. Then, based on the small integer solution problem, our scheme is provable secure in the random oracle model. Furthermore, compared with the previous self-certified signature schemes, our scheme is more secure. [ABSTRACT FROM AUTHOR]

A personal health record (PHR) is an electronic application which enables patients to collect and share their health information. With the development of cloud computing, many PHR services have been outsourced to cloud servers. Cloud computing makes it easier for patients to manage their personal health records and makes it easier for doctors and researchers to share and access this information. However, due to the high sensitivity of PHR, a series of security protections are needed to protect them, such as encryption and access control. In this article, we propose an attribute set-based Boolean keyword search scheme, which can realize fine-grained access control and Boolean keyword search over encrypted PHR. Compared with the existing attribute-based searchable encryption, our solution can not only improve the flexibility in specifying access policies but also perform Boolean keyword search, which can meet the needs of large-scale PHR users. Furthermore, we simulate our scheme, and the experimental results show that our scheme is practical for PHR systems in cloud computing. [ABSTRACT FROM AUTHOR]

Hierarchical key assignment scheme is an efficient cryptographic method for hierarchical access control, in which the encryption keys of lower classes can be derived by the higher classes. Such a property is an effective way to ensure the access control security of Internet of Things data markets. However, many researchers on this field cannot avoid potential single point of failure in key distribution, and some key assignment schemes are insecure against collusive attack or sibling attack or collaborative attack. In this paper, we propose a hierarchical key assignment scheme based on multilinear map to solve the multigroup access control in Internet of Things data markets. Compared with previous hierarchical key assignment schemes, our scheme can avoid potential single point of failure in key distribution. Also the central authority of our scheme (corresponding to the data owner in IoT data markets) does not need to assign the corresponding encryption keys to each user directly, and users in each class can obtain the encryption key via only a one-round key agreement protocol. We then show that our scheme satisfies the security of key indistinguishability under decisional multilinear Diffie-Hellman assumption. Finally, comparisons show the efficiency of our scheme and indicates that our proposed scheme can not only resist the potential attacks, but also guarantee the forward and backward security. [ABSTRACT FROM AUTHOR]

Order-preserving encryption (OPE) that preserves the numerical ordering of plaintexts is one of the promising solutions of cloud security. In 2013, an ideally secure OPE, which reveals no additional information except for the order of underlying plaintexts, was proposed, along with the notion (mutable encryption) that ciphertexts can be changed. Unfortunately, even the ideally secure OPE can be vulnerable by inferring the underlying frequency of repeated plaintexts. To solve this problem, in 2015, Kerschbaum designed a frequency-hiding OPE (FH-OPE) scheme based on the notion of a randomized order under the strengthened security model. Later, Maffei et al. has shown that Kerschbaum's model is imprecise, which means no such OPE scheme can exist. Moreover, they provided a new FH-OPE scheme under the corrected security model. However, their scheme requires the order information of all the encrypted plaintexts as an input; therefore, it causes relatively high overhead during encryption. In this work, we propose a more efficient FH-OPE based on Maffei et al.' s security model and also present an improved update algorithm suitable for duplicate plaintexts. [ABSTRACT FROM AUTHOR]

With the advent of large-scale social networks, two communication users need to generate session keys with the help of a remote server to communicate securely. In the existing three-party authenticated key exchange (3PAKE) protocols, users' passwords need to be stored on the server; it cannot resist the server disclosure attack. To solve this security problem, we propose a more efficient 3PAKE protocol based on the verification element by adopting a public-key cryptosystem and approximate smooth projection hash (ASPH) function on an ideal lattice. Using the structure of separating authentication from the server, the user can negotiate the session key only after two rounds of communication. The analysis results show that it can improve the efficiency of computation and communication and resist the server disclosure attack, quantum algorithm attack, and replay attack; moreover, it has session key privacy to the server. This protocol can meet the performance requirement of the current communication network. [ABSTRACT FROM AUTHOR]

Searchable public key encryption supporting conjunctive keyword search is an important technique in today's cloud environment. Nowadays, previous schemes usually take advantage of forward index structure, which leads to a linear search complexity. In order to obtain better search efficiency, in this paper, we utilize a tree index structure instead of forward index to realize such schemes. To achieve the goal, we first give a set of keyword conversion methods that can convert the index and query keywords into a group of vectors and then present a novel algorithm for building index tree based on these vectors. Finally, by combining an efficient predicate encryption scheme to encrypt the index tree, a tree-based public key encryption with conjunctive keyword search scheme is proposed. The proposed scheme is proven to be secure against chosen plaintext attacks and achieves a sublinear search complexity. Moreover, both theoretical analysis and experimental result show that the proposed scheme is efficient and feasible for practical applications. [ABSTRACT FROM AUTHOR]

In order to ensure the confidentiality and secure sharing of speech data, and to solve the problems of slow deployment of attribute encryption systems and fine-grained access control in cloud storage, a speech encryption scheme based on ciphertext policy hierarchical attributes was proposed. First, perform hierarchical processing of the attributes of the speech data to reflect the hierarchical structure and integrate the hierarchical access structure into a single-access structure. Second, use the attribute fast encryption framework to construct the attribute encryption scheme of the speech data, and use the integrated access to the speech data; thus, the structure is encrypted and uploaded to the cloud for storage and sharing. Finally, use the hardness of decisional bilinear Diffie–Hellman (DBDH) assumption to prove that the proposed scheme is secure in the random oracle model. The theoretical security analysis and experimental results show that the proposed scheme can achieve efficient and fine-grained access control and is secure and extensible. [ABSTRACT FROM AUTHOR]

In public-key encryption (PKE), ciphertexts received by a receiver may be possibly correlated and the security of a PKE relies on honestly generated system parameters. Security against selective opening attacks (SOA) for PKE guarantees that even when an attacker has broken into a subset of honestly generated ciphertexts and opened them (i.e., seeing plaintexts and random bits), the unopened ciphertexts remain secure. While security against parameter subversion attacks (PSA) for PKE requires that even when the public system parameters are maliciously generated, a PKE scheme should be secure. In this paper, we initiate the study of PKE secure against both SOA and PSA. To capture SOA and PSA simultaneously, we formulate a new security notion called indistinguishability under selective opening attacks and parameter subversion attacks (IND-SO-PSA). Further, we define the lossy trapdoor function and all-but-many lossy trapdoor function in the presence of PSA (LTF-PSA and ABM-LTF-PSA correspondingly) and propose an instantiation with the efficiently-embeddable group (EG). Applying these new primitives, we construct a PKE scheme that is proven to be IND-SO-PSA secure. [ABSTRACT FROM AUTHOR]

The previous encryption methods of hospital financial data have the problem of overburden. Therefore, a research study on hybrid encryption of hospital financial data based on Noekeon algorithm is proposed. From the basic principles of the Noekeon algorithm and the application and implementation of the Noekeon algorithm, a hybrid encryption scheme for hospital financial data based on the Noekeon algorithm is designed. In order to improve the security of the encryption system, the RSA algorithm is used to encrypt the encrypted content twice. The hybrid algorithm realizes the hybrid encryption of the hospital's financial data. Finally, a hybrid encryption system for hospital financial data based on Noekeon algorithm is designed. Experimental results show that this method has a higher success rate and better comprehensive performance. It not only improves the encryption efficiency of hospital financial data but also enhances the security of hospital financial data, which has greater application value. [ABSTRACT FROM AUTHOR]

Wireless body area network (WBAN) consists of a number of sensors that are worn on patients to collect dynamic e-health records (EHRs) and mobile devices that aggregate EHRs. These EHRs are encrypted at mobile devices and then uploaded to the public cloud for storage and user access. To share encrypted EHRs with users effectively, help users retrieve EHRs accurately, and ensure EHRs confidentiality, a secure multi‐keyword search and access control (SMKS-AC) scheme is proposed, which implements encrypted EHRs access control under the ciphertext-policy attribute-based encryption (CP-ABE). SMKS-AC provides multi‐keyword search for accurate EHRs retrieval, supports the validation of decrypted EHRs, and traces and revokes the identity of users who leak private key. Security analysis shows that SMKS-AC is secure against chosen keyword and chosen plaintext attacks. Through theoretical analysis and experimental verification, the proposed SMKS-AC scheme requires less storage resources and computational costs on mobile devices than existing schemes. [ABSTRACT FROM AUTHOR]

Wireless sensor networks (WSN) have problems such as limited power, weak computing power, poor communication ability, and vulnerability to attack. However, the existing encryption methods cannot effectively solve the above problems when applied to WSN. To this end, according to WSN's characteristics and based on the identity-based encryption idea, an improved identity-based encryption algorithm (IIBE) is proposed, which can effectively simplify the key generation process, reduce the network traffic, and improve the network security. The design idea of this algorithm lies between the traditional public key encryption and identity-based public tweezers' encryption. Compared with the traditional public key encryption, the algorithm does not need a public key certificate and avoids the management of the certificate. Compared with identity-based public key encryption, the algorithm addresses the key escrow and key revocation problems. The results of the actual network distribution experiments demonstrate that IIBE has low energy consumption and high security, which are suitable for application in WSN with high requirements on security. [ABSTRACT FROM AUTHOR]