Efficiently-Searchable and Deterministic Asymmetric Encryption

Outsourcing data storage is a topic of emerging importance in database security. Inthis paper, we consider exact-match query functionality in the public-key setting. Solutionsproposed in the database community lack clarity and proofs of security, while encryption-with-keyword-search schemes from the cryptographic community require linear search time(in database size) for each query, which is prohibitive. To bridge the gap, we introduce anew cryptographic primitive we call (asymmetric) efficiently-searchable encryption (ESE),which allows users to store encrypted data on a remote, untrusted server in such a waythat the server can index the data and retrieve or update required parts on request just asefficiently as for unencrypted data. We give an appropriate definition of security for ESEand several constructions that provably-achieve the definition, in the random oracle model,while providing various computationand bandwidth-efficiency properties. As deterministicencryption implies ESE, the security definition and several of the constructions are also thefirst for asymmetric deterministic encryption schemes in general.