Refine the Concept of Public Key Encryption with Delegated Search
The authors revisit the concept of Public Key Encryption with Delegated keyword Search (PKEDS), a concept proposed by Ibraimi et al. A PKEDS scheme allows a receiver to authorize third-party server(s) to search in two ways: either according to a message chosen by the server itself or according to a trapdoor sent by the receiver. They show that the existing formulation has some defects and the proposed scheme is unnecessarily inefficient. Based on their analysis, they present a refined formulation of the primitive with a new security model. They then propose a new PKEDS scheme, which is proven secure and much more efficient than the original scheme by Ibraimi et al.