Fine-grained searchable encryption in multi-user setting

In order to share resources conveniently, users often store their data on remote cloud servers. However, to ensure the security, data will be encrypted when outsourcing to the cloud. This brings some trouble for data search. Searchable encryption allows users to search over the encrypted data on cloud storage to retrieve the interested data without decryption. However, in most of the existing schemes all the encrypted data are treated in the same way. Every user can search for it. In this paper, a fine-grained searchable encryption scheme with two non-colluding cloud servers is proposed. In this scheme, the files can be retrieved if and only if user’s attributes satisfy the access policy and the required keyword agrees with the file keyword. And users can verify whether the cloud server executes the search all over the ciphertexts. Besides, the removed user cannot search again even if he/she colludes with one of the servers.