Two Variants Of Public Key Encryption With Keyword Search Schemes

The notion of public key encryption with keyword search was first introduced by Boneh in 2004,which enables users to search the encrypted data from the third party by using a particular keyword.In a public key encryption with keyword search scheme,users use his or her secret key to generate the trapdoor Tw of the keyword w,then transfer the corresponding Tuw to the server.The server can help find out the encrypted documents that contain the keyword ? by using the knowledge of the trapdoor.After the search,the server returns the related encrypted documents to the user.Within that process,the server can learn nothing about users' privacy.Nevertheless,Boneh et al.'s public key encryption with keyword search scheme needs a secure channel to transfer the trapdoor.At the same time,the scheme cannot effectively encrypt multiple keywords and fails to resist the off line keyword guessing attack from the outside attacker.To resolve this three problems,we propose two public key encryption with keyword search schemes:1.We integrate the secure channel free public key encryption with keyword search scheme and the searchable encryption scheme with multiple keywords,and pro-pose a new type of searchable encryption scheme called An Efficient Secure Channel Free Searchable Encryption Scheme with Multiple Keywords.The scheme can not only effectively encrypt multiple keywords,but also remove the secure channel between the receiver and the server.In the random oracle mod-el,the scheme is proved to be secure under the assumption that the BDH and 1-BDHI problems are hard.The simulation results demonstrate our scheme is applicable in the real life.2.We integrate the secure channel free public key encryption with keyword search scheme and the trapdoor indistinguishable public key encryption with keyword search scheme,and propose a new type of searchable encryption scheme called An Enhanced Searchable Encryption Scheme from Bilinear Pairings.In the assumption of two complexity problems BDH and BDHI,we prove that our scheme satisfies ciphertexts indistinguishable under adaptively chosen keyword attack.Moreover,in the assumption of the problem HDH,we prove that our scheme satisfies trapdoor indistinguishable under adaptively chosen keyword attack.The performance analysis shows the scheme possesses better efficiency.