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The space-air-ground integrated network (SAGIN) has a stringent demand on the efficiency of authentication protocols deployed in the devices that have been launched into the air and space. In this article, we define the concept of the security model of conditional physical unclonable function (CPUF) that guarantees the security of the protocol while allowing the use of PUFs that can be modeled. We then propose a CPUF-based authentication and key agreement (AKA) scheme, named CPAKA, that addresses the challenges of device key leakage and inefficient authentication in resource-asymmetric environments. The CPAKA scheme embeds PUFs in weak nodes and deploys prediction models corresponding to the PUFs in strong nodes, eliminating the need to store challenge-response pairs or perform complex calculations. We formally prove the protocol's security under the decisional uniqueness assumption of CPUF and the universal composability framework, and we analyze its secrecy and authentication properties using the Tamarin prover. We also implement an Arbiter PUF on the ZYNQ-7020 FPGA, verify its accuracy through experiments, and show that CPAKA is secure, efficient, and suitable for SAGIN. Our CPAKA scheme greatly reduces computing and storage costs while improving authentication efficiency compared to traditional schemes.

The cloud-edge-end architecture is suitable for many essential scenarios, such as 5G, the Internet of Things (IoT), and mobile edge computing. Under this architecture, cross-domain and cross-layer data sharing is commonly in need. Considering cross-domain data sharing under the zero-trust model, where each entity does not trust the others, existing solutions have certain problems regarding security, fairness, scalability, and efficiency. Aiming at solving these issues, we conduct the following research. First, a new plaintext checkable encryption scheme is constructed, which can be used on lightweight IoT devices to verify the ciphertext validity sent by a data owner. Second, we propose a new multi-domain cloud-edge-end architecture based on sharding blockchains and design a cross-domain data sharing scheme under the partial trust model to achieve security, scalability, and high performance. Third, a cross-domain data sharing scheme under the zero trust model is further designed, which can ensure the fairness of both parties in data sharing. Fourth, we give a formal security definition and analysis of cross-domain data sharing. Fifth, we conduct a detailed theoretical analysis of the protocol and give an in-depth functional test and performance test, including the throughput and latency of data sharing policy registration and execution.

Due to the rapid development of demand response management and distributed energy resources, prosumers are becoming more proactive, which also promotes the emergence of peer-to-peer (P2P) energy trading mechanisms. However, we find that it is quite difficult to simultaneously achieve high computational efficiency, decentralized operations and solution optimality in a P2P energy trading mechanism, which is called the “P2P energy trading trilemma”. In this paper, we first propose a novel negotiation mechanism for P2P energy trading that can maximize social welfare in a decentralized manner and respect physical network constraints. Then, the local optimization problem is transformed into a closed-form alternating update algorithm (AUA), so that the computational efficiency can be greatly improved. Therefore, our proposed mechanism solves the “P2P energy trading trilemma” to a certain extent. Another challenge is that the locational marginal price (LMP)-based market mechanism cannot satisfy the incentive-compatible property. To encourage prosumers to cooperate in a lack-of-trust environment, a novel incentive-compatible mechanism is proposed for P2P energy trading using consensus mechanism inspired by proof of solution (PoSo) and smart contract (SC). Finally, we simulate the functionality of the mechanism in terms of convergence performance, reliability, scalability, computational efficiency, and SC operations.

Recently, an emerging branch of research in the field of fully homomorphic encryption (FHE) attracts growing attention, where optimizations are carried out in developing fast and efficient homomorphic logic circuits. While existing works have pointed out that compound homomorphic gates can be constructed without incurring significant computational overheads, the exact theory and mechanism of homomorphic gate design have not yet been explored. In this work, we propose AutoHoG, an automated procedure for the generation of compound gates over FHE. We show that by formalizing the gate generation procedure, we can adopt a match-and-replace strategy to significantly improve the evaluation speed of logic circuits over FHE. In the experiment, we first show the effectiveness of AutoHoG through a set of benchmark gates. We then apply AutoHoG to optimize common Boolean tasks, including adders, multipliers, the ISCAS’85 benchmark circuits, and the ISCAS’89 benchmark circuits. We show that for various circuit benchmarks, we can achieve up to $5.7\times $ reduction in computational latency when compared to the state-of-the-art implementations of logic circuits using conventional gates.

Cloud computing has become an increasingly popular option for users to store and share data. Encryption prior to outsourcing data to the cloud is the best way to protect data security and privacy; however, it hinders sharing of the data that was encrypted. In addition, users in many real-world organizations (e.g., enterprises) have multiple level structures and a higher-level user should have the privilege to decide which data can be shared with a lower-level user. Most solutions in the literature suffer from inefficiency or inflexibility in tackling this problem. In this article, we propose a fine-grained hierarchical data sharing (FHDS) scheme in clouds. With FHDS, the data owner can encrypt data with his public key, and then selectively share encrypted data with users in a hierarchy; if necessary, the users can disseminate the owner's data to their subordinates in the lower levels by generating access keys. In particular, the higher-level users could puncture the keys with some tags such that the part of the owner's data which is labeled by the punctured tags will not be accessible to the lower-level users. The proposed scheme is provable secure under our security model and performance analyses show the efficiency of the scheme.