Research on Searchable Encryption for Expandable Multi-Type Groups

Searchable encryption can effectively ensure the confidentiality of data stored in the untrusted third parties by encrypting the data, while also having the function of searching. However, with the increasing complexity of online services, the demand for multi-user data sharing on third-party platforms is becoming increasingly important and complex in form. Single user searchable encryption schemes are difficult to meet current needs. In response to this issue, this article proposes a searchable encryption scheme for expandable group types, which supports the establishment of multiple group relationships. We combine the hierarchical group key distribution protocol with single-user searchable encryption, and the hierarchical group key distribution protocol effectively maintains the management of the group. Legitimate members within the group can upload, search, and download encrypted data. This scheme constructs three different search encryption data patterns for different groups, namely long-term stable groups, temporary dynamic groups, and groups established between groups. Compared to the current many to many user searchable encryption schemes (which generally only support long-term stable groups), this scheme can achieve more flexible encrypted data search within and between groups. Under the framework of this scheme, any single user searchable encryption scheme can be extended to achieve secure data sharing among multiple groups. Multi functional searchable encryption schemes can be selected according to needs, and it is also easy to transplant into other existing schemes, making the application more convenient. In terms of security, it can resist more types of collusion attacks and improve the security of the scheme.