Searchable encryption (SE) enables the client to execute keyword searches in encrypted data stored on the untrusted server and has been widely studied in cloud storage. To achieve higher efficiency and more functionalities, most SE schemes allowed the client to leak some information to the server. These leaked information are commonly referred to as leakage patterns. There are three important leakage patterns: search pattern, access pattern and volume pattern. Recent research has exploited at least one of these three patterns to attack SE schemes, resulting in the compromise of the confidentiality of encrypted data and queried keywords. Although existing SE schemes support conjunctive keyword search and protect these three patterns, these schemes do not support disjunctive keyword search and have a higher computational cost. In this paper, we use a private set union protocol based on additively symmetric homomorphic encryption to construct an SE scheme, which not only protects three patterns but also supports disjunctive keyword search. Specifically, we design an efficient token generation algorithm to protect the search pattern and a non-naive padding method to protect the volume pattern. Furthermore, we prove the correctness of our scheme through theoretical analysis and strictly prove the security under the leakage function. Finally, performance evaluation demonstrates that our scheme supports disjunctive keyword search while achieving a favorable trade-off between leakage protection and efficiency. Moreover, for components that exhibit relatively higher overhead during evaluation, we introduce optimization strategies that effectively enhance search efficiency and scalability.

Verifiable searchable encryption (VSE) not only allows the client to search encrypted data, but also allows the client to verify whether the server honestly executes search operations. Currently, VSE scheme has been widely studied in cloud storage. However, most existing VSE schemes did not hide the access pattern and volume pattern, which respectively refer to the document identifiers and the number of documents matching the queried keywords. Recent studies have exploited these two patterns to launch attacks on searchable encryption schemes, resulting in compromising the confidentiality of encrypted data and queried keywords. In order to solve above issues, we utilize additively symmetric homomorphic encryption scheme and private set intersection protocol to construct a VSE scheme that supports conjunctive keyword search and hides the access pattern and volume pattern (i.e., response-hiding and volume-hiding). Our security model assumes that the server is malicious in the sense that it might deliberately carry out incorrect search operations. Formal security analysis demonstrates that our scheme achieves the desired security properties under our leakage function. Compared to previous schemes, our scheme has advantages in terms of performance and functionality. In an experimental setup with a security parameter of 128 bits and$2^{23}$keyword/document pairs, the search time is approximately only 7.18 seconds.

Searchable symmetric encryption (SSE) allows the client to search encrypted documents on an untrusted server without revealing the document content and queried keywords. To improve search efficiency and enrich expressiveness, most SSE schemes leak some information that could be exploited for attacks, characterized by leakage patterns. The traditional leakage patterns encompass the search pattern, the access pattern and the response length pattern. Recent research has demonstrated that these three patterns could be exploited to launch attacks, resulting in a high probability of compromising the confidentiality of encrypted documents and queried keywords. Moreover, while there exist SSE schemes that hide multiple leakage patterns, most of them do not resist the malicious server, which may carry out incorrect search operations. In this paper, we propose a leakage-suppressed verifiable SSE (VSSE) scheme that not only hides the three patterns but also allows the client to verify the server’s response. We utilize the privacy set intersection based on polynomial coding and additive symmetric homomorphism encryption to construct a VSSE scheme that supports a conjunctive query. Specifically, we design an efficient random token generation algorithm to protect the search pattern and a verification algorithm that does not require server-generated proofs. Formal security analysis shows that our scheme achieves the desired correctness, security and verifiability. Lastly, we simulate the proposed scheme and compare it with the recent leakage suppression schemes in multiple aspects. The comparison results show that our scheme achieves a good balance in expressiveness, efficiency and security.