In Internet of Things (IoT) application scenarios such as intelligent logistics, secure data access control and sharing based on dynamic searchable symmetric encryption (DSSE) has become a research hotspot in recent years. DSSE is an encryption technology which gratifies the above requirements, while protecting the sensitive data during the operation. The existing DSSE schemes do not achieve data deduplication and conjunctive queries concurrently, and exist problems such as complex update process, inflexible query method and privacy disclosure, etc. For this purpose, the paper proposes dynamic searchable symmetric encryption for data deduplication and conjunctive queries (DSSE-DC), and constructs a concrete DSSE-DC scheme. Our scheme uses symmetric encryption with homomorphic addition and bitmap index to develop a secure and reliable search architecture, and updates through modular addition. Meanwhile, we add a deduplication mechanism to realize data deduplication which avoids the waste of cloud storage resources. Furthermore, we introduce the idea of inner product matching to achieve efficient conjunctive queries. The adaptive security of DSSE-DC scheme is proved in the random oracle model. Whilst our scheme satisfies forward and backward privacy. In comparison to the existing DSSE schemes for conjunctive queries, our scheme has advantage in update and search performances, which is applicable to IoT applications like intelligent logistics.

Users are inclined to outsource their data to the cloud due to the rapid growth of data in response to the growing use of cloud computing and the Internet of Things (IoT). One of the primary issues for users is the secure sharing of personal data. Access control and fine-grained sharing of encrypted data can be accomplished with attribute-based encryption (ABE). However, the computational cost required for ABE decryption hinders its widespread deployment on lightweight devices. For lightweight mobile devices, outsourcing computation is a highly attractive technical that outsources heavy decryption tasks to the cloud. The majority of current outsourced ABE schemes, however, only verify whether the cloud returns the correct decryption result, and lack a mechanism to prevent mobile devices from maliciously accusing the cloud of returning incorrect results, and overlook fairness between mobile devices and the cloud. Furthermore, the increasing number of encrypted files stored in the cloud will impede efficient query processing. Moreover, attribute revocation and privacy protection are also crucial. Therefore, this paper proposes fair-and-exculpable-attribute-based searchable encryption with revocation and verifiable outsourced decryption (FE-ABSE-RV) Using Smart Contract, and constructs a concrete FE-ABSE-RV scheme. The scheme is capable of withstanding chosen plaintext attack and chosen keyword attack according to security analysis. Theoretical analysis and simulation experiments illustrate that the FE-ABSE-RV scheme is more expressive, efficient, and practical.

Data security is becoming increasingly critical as outsourced data services flourish. An effective solution for ensuring data confidentiality in the cloud is attribute-based searchable encryption (ABSE). However, most extant ABSE solutions have not been able to simultaneously achieve rich expressive queries, result validation, attribute revocation, and policy hiding, and there are problems such as inflexibility in query methods and access control capabilities, insufficient scalability and practicality, and privacy leakage. In particular, it should be noted that most ABSE schemes fail to promise the privacy security of access policies and are susceptible to offline keyword guessing attack. Hidden policy-ABSE (HP-ABSE) has been proposed to tackle the issue of explicit attribute values in access policies potentially compromising privacy. Nevertheless, in most existing HP-ABSE schemes, an adversary may initiate attribute values guessing attack to speculate on the values of attribute within access strategy. To this end, this paper proposes partially hidden policy attribute-based multi-keyword searchable encryption with verification and revocation (PHP-ABMKSE-VR). PHP-ABMKSE-VR scheme is practical, secure, as well as effective, making it appropriate for real-world scenarios like smart healthcare, as demonstrated by the experimental outcomes and safety analysis.

In recent years, many cloud service providers adopt the pay-per-query model to offer paid search services to the public. The data owner rents the resources of cloud service providers and charges the data user a fee based on the data volume to be queried. While this commercial model offers flexibility, convenience, and cost-effectiveness, it comes with a significant vulnerability to data breaches. Public-key authentication encryption with keyword search (PAEKS) is a technology which is well applied in the pay-per-query model. But there is no PAEKS scheme applicable to this scenario. For this purpose, we present public-key authentication encryption with similar data search for pay-per-query (PAESS) and construct the first idiographic scheme PAESS-I. PAESS-I utilizes Shamir secret sharing and locality sensitive hashing to implement similar data search, has the verifiability of results, adds the charge function to prevent cloud servers and data users from colluding to deny deductions. We propose the second scheme PAESS-II based on PAESS-I, which is a mobile-friendly lightweight PAESS. Our second scheme operates in the pay-per-query model without pairing and exponential operations. PAESS-I satisfies ciphertext indistinguishability and trapdoor indistinguishability, and sacrifices the computational performance in favor of the pay-per-query model. The optimized PAESS-II is resistant to adaptively-chosen-targets attack, and satisfies ciphertext indistinguishability and trapdoor indistinguishability. PAESS-II distinguishes itself from other existing similar schemes by having the same characteristics as PAESS-I, along with the benefits when it comes to the calculation cost.

In recent years, many extended identity-based broadcast proxy re-encryption (IBPRE) schemes have been put forward. These schemes are flexible enough and feasible to various application scenarios, including conditional IBPRE, revocable IBPRE, and anonymous IBPRE. However, the existing extended IBPRE schemes are not able to simultaneously achieve fine-grained data sharing, identity privacy protection for authorized data users (DUs) and access privilege revocation. To this end, we put forward conditional identity-based broadcast proxy re-encryption with anonymity and revocation (CIBPRE-AR) and construct a concrete CIBPRE-AR scheme. The scheme implements fine-grained data sharing by associating conditions with the re-encryption key. The identity privacy protection for authorized DUs is provided by using Lagrange interpolation. Further, the access privileges of the violated DU are revoked by updating the re-encryption key. The indistinguishability of ciphertexts against chosen-plaintext attack and anonymity of the DUs are proved rigidly. Compared with existing similar schemes, only the CIBPRE-AR scheme simultaneously achieves fine-grained data access control, anonymity as well as revocation. The proposed scheme also has advantage with respect to computation cost.