Public Key Timed-Release Searchable Encryption

This paper introduces and explores a new concept of timed-release searchable encryption (TRSE) which can be used to solve the time-sensitive cipher text retrieval problem. In this paper, we preliminarily focus on the PKTRSE which is a kind of public key TRSE. In our PKTRSE model, the sender encrypts a message so that only the intended receiver can search target cipher text containing specified keywords after a pre-set release time in the future. We begin by explaining what is PKTRSE and introducing the application scenario of PKTRSE. Then, we show the preconditions of timed-release public key encryption combining other asymmetric crypto-graphic mechanisms. Afterwards, we formalize the notion of PKTRSE and its security game model. Finally, we give two construction schemes of PKTRSE: A generic scheme and a concrete scheme which are secure under the BDH assumption in the random oracle model.