Designated-Server Hierarchical Searchable Encryption in Identity-Based Setting

Public key encryption with keyword search (PEKS) is a cryptographic primitive designed for performing secure search operations over encrypted data stored on untrusted cloud servers. However, in some applications of cloud computing, there is a hierarchical access-privilege setup among users so that upper-level users should be able to monitor data used by lower-level ones in the hierarchy. To support such situations, Wang et al. introduced the notion of hierarchical ID-based searchable encryption. However, Wang et al.'s construction suffers from a serious security problem. To provide a PEKS scheme that securely supports hierarchical structures, Li et al. introduced the notion of hierarchical public key encryption with keyword search (HPEKS). However, Li et al.'s HPEKS scheme is established on traditional public key infrastructure (PKI) which suffers from costly certificate management problem. To address these issues, in this paper, we consider designated-server HPEKS in identity-based setting. We introduce the notion of designated-server hierarchical identity-based searchable encryption (dHIBSE) and provide a formal definition of its security model. We then propose a dHIBSE scheme and prove its security under our model. Finally, we provide performance analysis as well as comparisons with related schemes to show the overall superiority of our dHIBSE scheme.