Flexible Attribute-Based Keyword Search via Two Access Policies

Abstract

Attribute-based keyword search (ABKS) allows users, whose credentials satisfy the owner’s access control policy, to search over the encrypted data in cloud environment. However, most current schemes can not simultaneously achieve that owners dominate the data while users retrieve the interested files more accurately, either in ciphertext policy or key policy setting. Furthermore, majority of ABKS schemes ignore the decryption of retrieved files, or focus little about decryption efficiency. Therefore, aiming at these limitations, we propose a flexible attribute based keyword search scheme via two access policies, which allows: (1) the data owner to control the access policy in order to gain control over their data and specify who can access the files; (2) the user to define the search policy so that he can search the interested encrypted files more accurately. In addition, we employ an online/offline technique to improve the efficiency. And the ciphertexts can be decrypted with two pairings while it grows linear with the number of attributes in most existing schemes. Our system is selectively secure against chosen-plaintext attack and chosen-keyword attack, and it also achieves keyword secrecy.