Multi-Keyword Search with a Threshold for Cloud-Based Group Data Sharing

A common cryptographic basic, Searchable Encryption (SE), is used in the development of ciphertext retrieval systems that have a wide range of applications. Current SE methods, on the other hand, do not often provide threshold access control (i.e., data users must collaborate to perform search and decryption operations over encrypted cloud data), which is becoming more popular in the research community. Beginning with the most basic TMS scheme, we provide a Shamir's secret sharing technique for cloud-based group data sharing, which incorporates Threshold Multi-keyword Search (TMS) with Shamir's secret sharing technique to achieve threshold multi-keyword search, threshold decryption, and a small record ciphertext size. Then, we build on top of this fundamental TMS to provide threshold result verification as well as threshold traceability (referred to as enhanced TMS). Furthermore, the enhanced TMS has been upgraded to enable public result verification as well as dynamic operations using the public verifier and better hash tables, which are also included in the enhanced TMS package. Both the basic TMS and the improved TMS are semi-adaptively secure, and they can withstand the Chosen Keyword Attack, as shown by our rigorous security study (CKA). Our theoretical assessment and practical tests show that both systems have the potential to be beneficial.