Electronic cash (e-cash) payment is facing the privacy leakage, money laundering and tax evasion. To address these issues, we use SM2-based blind signcryption to construct a decentralized e-cash payment scheme (DECPS). SM2-based blind signcryption allows a signcrypter to generate a ciphertext with unknown message content. Double spending is prevented because the blockchain uploads the e-cash to public chain for transparency. DECPS has low calculation overhead for scalar multiplication and there is no key escrow. In addition, the pseudo-random number generator (RNG) is used to trace illegal transactions.

To solve the privacy leakage and identity island problems in cross-chain interaction, we propose an anti-quantum cross-chain identity authentication approach based on dynamic group signature (DGS-AQCCIDAA) for smart education. The relay-based cross-chain model promotes interconnection in heterogeneous consortium blockchains. DGS is used as the endorsement strategy for cross-chain identity authentication. Our approach can ensure quantum security under the learning with error (LWE) and inhomogeneous small integer solution (ISIS) assumptions, and it uses non-interactive zero-knowledge proof (NIZKP) to protect user identity privacy. Our scheme has low calculation overhead and provides anonymous cross-chain identity authentication in the smart education system.

To ensure the quantum security requirement in Internet of Things (IoT) scenarios, we first propose certificateless anti-quantum blind signature (CLAQBS) for blockchain-based logistics donation system in IoT scenario, its security relies on the hardness of small integer problem on ring in number theory research unit lattice; the ethereum lightning network enhances the transaction speed of consortium blockchain and the rejection sampling algorithm improves the signature speed; it has short signature key and high-execution efficiency. Then, we propose certificateless anti-quantum sequential aggregate signature (CLAQSAS) for IoT intelligent invoice system, the signer performs sequential aggregate signature on invoice information of each different goods to generate a new signature; it ensures the anti-quantum security because of the unique nonsampling algorithm, trapdoor generation algorithm and matrix preimage sampling algorithm in lattice.

Electronic healthcare systems can offer convenience but face the risk of data forgery and information leakage. To solve these issues, we propose an identity-based searchable attribute signcryption in lattice for a blockchain-based medical system (BCMS-LIDSASC). BCMS-LIDSASC achieves decentralization and anti-quantum security in the blockchain environment, and provides fine-grained access control and searchability. Furthermore, smart contracts are used to replace traditional trusted third parties, and the interplanetary file system (IPFS) is used for ciphertext storage to alleviate storage pressure on the blockchain. Compared to other schemes, BCMS-LIDSASC requires smaller key size and less storage, and has lower computation cost. It contributes to secure and efficient management of medical data and can protect patient privacy and ensure the integrity of electronic healthcare systems.

Development of Agriculture 4.0 brings higher demands for managing agricultural products. Blockchain technology can enhance the transparency, traceability, and security of the supply chain. Traditional single-blockchain model faces the scalability limitations. Therefore, we propose multilayer blockchain system for agricultural data management to enable the precise management in various aspects, such as supply chain tracing, land management, market transactions, and sustainability tracking. Interplanetary file system helps to alleviate the burden on data storage. Based on the characteristics of system data flow, we devise a post-quantum cross-blockchain data exchange approach using attribute-based encryption (ABE-PQCBCDEA). It solves the scalability problem and realizes fine-grained access control of different blockchain data, and it significantly reduces the size of ciphertext sets for ciphertext reuse. ABE-PQCBCDEA obtains the 42.6% improvement in the encryption and decryption efficiency compared with previous approaches, and its communication costs have been reduced by 48.5%, thereby it reduces the burden of cross-chain data exchange.

Number theory research unit (NTRU) lattice has small storage space, high execution efficiency and anti-quantum security. To obtain the quantum immunity and high efficiency in electronic voting, we devise certificateless ring signature from NTRU lattice (NTRUL-CLRS) for electronic voting in this article. Security of NTRUL-CLRS relies on the small integer solution on ring (R-SIS) assumption. Rejection sampling technique is used to generate the ring signature and so the signature speed is greatly improved. NTRUL-CLRS has the quantum immunity, unconditional anonymity and unforgeability; it is suitable for application in electronic voting system because it simplifies the electronic voting process and reduces the electronic voting cost.

Threshold signature can solve the problems of high cost and network congestion during the execution of smart contracts. However, the information transmitted in public links is vulnerable to eavesdropping, tampering and other network attacks, it is essential to ensure the confidentiality and integrity during data transmission. However, traditional threshold signcryption is not suitable for blockchain setting and cannot withstand the quantum computing attacks. In view of these reasons, one lattice-based threshold signcryption for blockchain oracle data transmission (BCODT-LTSC) is devised in this article. BCODT-LTSC satisfies the existential unforgeability, confidentiality and threshold characteristic; it has very low computation cost and is suitable for the application in blockchain scenario.

Network coding can save wireless network resources and is very fast in comparison with traditional routing. In real application scenarios, network coding is vulnerable to pollution attacks and forgery attacks. To solve these problems, the certificateless broadcast multi-signature for network coding (NC-CLBMS) method is devised, where each source node user generates a multi-signature about the message vector, and the intermediate node linearly combines the received data. NC-CLBMS is a multi-source multi-signature method with anti-pollution and anti-forgery advantages; moreover, it has a fixed signature length and its computation efficiency is very high. NC-CLBMS has extensive application prospects in unmanned aerial vehicle (UAV) communication networks, fifth-generation wireless networks, wireless sensor networks, mobile wireless networks, and Internet of Vehicles.

Blind signcryption (BSC) can guarantee the blindness and untrackability of signcrypted messages, and moreover, it provides simultaneous unforgeability and confidentiality. Most traditional BSC schemes are based on the number theory. However, with the rapid development of quantum computing, traditional BSC systems are faced with severe security threats. As promising candidate cryptosystems with the ability to resist attacks from quantum computing, lattice-based cryptosystems have attracted increasing attention in academic fields. In this paper, a post-quantum blind signcryption scheme from lattice (PQ-LBSCS) is devised by applying BSC to lattice-based cryptosystems. PQ-LBSCS inherits the advantages of the lattice-based cryptosystem and blind signcryption technique. PQ-LBSCS is provably secure under the hard assumptions of the learning with error problem and small integer solution problem in the standard model. Simulations are carried out using the Matlab tool to analyze the computational efficiency, and the simulation results show that PQ-LBSCS is more efficient than previous schemes. PQ-LBSCS has extensive application prospects in e-commerce, mobile communication, and smart cards.

A (t,n) threshold signcryption scheme makes the distributor authorize a group with n members, any t or more signcrypters can cooperatively use the signcryption keys to sign the message; however, t−1 or fewer signcrypters cannot. Threshold signcryption has broad applications in the electronic auction, electronic election, distributed environment, cloud computing and block chain. In this paper, we combine the threshold signcryption with certificateless cryptosystem to construct a secure and efficient certificateless threshold signcrypton scheme with secret sharing mechanism (SSM-CLTSCS), which is provably indistinguishable and unforgeable under the hardness of the DBDH (decisional bilinear Diffie–Hellman) and CDH (computational Diffie–Hellman) problems. Analysis shows SSM-CLTSCS outperforms the existing schemes in computational efficiency; and so it will obtain much more attention in the application fields of information security.

Traditional certificateless ring signature is not suitable for the network coding environment. In this view, a new certificateless network coding ring signature (CL-NCRS) is devised by using the techniques of multisource network coding and certificateless ring signature. Network coding is a kind of information interaction technology and can improve system robustness and save wireless network resources. CL-NCRS satisfies the unforgeability and unconditional anonymity; moreover, it has relatively higher communication and computational efficiency.

Cloud computing provides a new, attractive paradigm for the effective sharing of storage and computing resources among global consumers. More and more enterprises have begun to enter the field of cloud computing and storing data in the cloud to facilitate the sharing data among users. However, in many cases, users may be concerned about data privacy, trust, and integrity. It is challenging to provide data sharing services without sacrificing these security requirements. In this paper, a data sharing scheme of reliable, secure, and privacy protection based on general access structure is introduced. The proposed scheme is not only effective and flexible, but also is capable of protecting privacy for the cloud owner, supporting data sharing under supervision, enabling accountability of users’ decryption keys, and identifying cheaters if some users behave dishonestly. Security analysis and efficiency analysis demonstrate that our proposed scheme has better performance in computational costs compared with most related works. The scheme is versatile to be used in various environments. For example, it is particularly suitable to be employed to protect personal health data and medical diagnostic data in information medical environment.

Proxy signcryption means that the proxy signcrypter obtains the delegate authorization from the original signcrypter and then signcrypts the specified message on behalf of the original signcrypter. In this paper, we construct an identity-based proxy signcryption protocol (IBPSP) based on the universally composable (UC) framework. In the random oracle model, we prove that this protocol has the semantic security under the gap bilinear Diffie-Hellman and computational Diffie-Hellman assumptions. At the same time, an ideal functionality of the identity-based proxy signcryption protocol is defined in the UC security framework, and we also prove the equivalence between the universally composable identity-based proxy signcryption protocol and its IND-CCA2 and UF-CMA security. Analysis shows this IBPSP has both low computation complexity and semantic security together with UC security.

Certificateless signcryption (CLSC) can simultaneously fulfill certificateless encryption and certificateless signature; however, most CLSC schemes need costly computational overhead due to the usage of pairing operations. How to improve its computational efficiency is a very significant research problem. In this paper, we propose a pairing-free and secure CLSC scheme. In the random oracle model, the proposed scheme is indistinguishability against adaptive chosen-ciphertext attacks secure in confidentiality and unforgeability against adaptive chosen-message attacks secure in unforgeability. In the new scheme, only a designated receiver can recover the message, and a third party can verify the validity of a signcrypted text without knowing the receiver's secret value. In addition, this cryptographic algorithm is very appropriate to applications in online auction, email system and private contractual signature.

Hybrid signcryption is an important technique signcrypting bulk data using symmetric encryption. In this paper, we apply the technique of certificateless hybrid signcryption to an elliptic-curve cryptosystem, and construct a low-computation certificateless hybrid signcryption scheme. In the random oracle model, this scheme is proven to have indistinguishability against adaptive chosen-ciphertext attacks (IND-CCA2) under the elliptic-curve computation Diffie-Hellman assumption. Also, it has a strong existential unforgeability against adaptive chosen-message attacks (sUF-CMA) under the elliptic-curve discrete logarithm assumption. Analysis shows that the cryptographic algorithm does not rely on pairing operations and is much more efficient than other algorithms. In addition, it suits well to applications in environments where resources are constrained, such as wireless sensor networks and ad hoc networks.