Abstract: Searchable encryption provides encryption and search at the same time. The current semantically secure searchable schemes provide search time linear with the total number of ciphertexts. This makes it less acceptable for large databases. Hence new techniques are adopted providing some hidden relations among the ciphertexts to improve the search efficiency. The search trapdoor finds out the first matching keyword and through hidden relations all the related ones could be found out. The search complexity now depends on the number of ciphertexts containing the queried keyword than on the total number of ciphertexts.

Keywords: public key-searchable encryption, Identity Based Encryption, Identity Based Key Encapsulation mechanism, Semantic security.