Towards Multi-user Searchable Encryption Scheme with Support for SQL Queries

Due to the tremendous benefits of cloud computing, organizations are highly motivated to store electronic records on clouds. However, outsourcing data to cloud servers separates it from physical control, resulting in data privacy disclosure. Although encryption enhances data confidentiality, it also complicates the execution of encrypted database operations. In this paper, we propose a multi-user shared searchable encryption scheme that supports multi-user selective authorization and secure access to encrypted databases. First, we apply the Diffie-Hellman protocol to a trapdoor generate algorithm to facilitate fine-grained search control without incremental conversions. Second, we utilize a private key to generate an encrypted index by bilinear mapping, which makes it impossible for an adversary to obtain trapdoor keywords by traversing the keyword space and to carry out keyword guessing attacks. Third, we use double-layered encryption to encrypt a symmetric decryption key. Only the proxies whose attributes are matched with the access control list can obtain the key of decrypted data. Through theoretical security analysis and experimental verifications, we show that our scheme can provide secure and efficacious ciphertext retrieval without the support of a secure channel. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.