Secure Index for Resource-Constraint Mobile Devices in Cloud Computing

With the rapid development of network technology and cloud computing, more and more organizations and users outsource their data into the cloud server. In order to protect data privacy, the sensitive data have to be encrypted, which increases the heavy computational overhead and brings great challenges to resource-constraint devices. In this paper, we propose secure index based on counting Bloom filter (CBF) for ranked multiple keywords search. In the proposed scheme, several algorithms are designed to maintain and lookup CBF, while a pruning algorithm is used to delete the repeated items for saving the space. Besides, the relevance scores are encrypted by the Paillier cryptosystem. It ensures that the same relevance scores are encrypted into different bits, which can resist the statistical analyses on the ciphertext of the relevance scores. Moreover, since the Paillier cryptosystem supports the homomorphic addition of ciphertext without the knowledge of the private key, the major computing work in ranking could be moved from user side to the cloud server side. Therefore, the proposed scheme has huge potentials in resource-constraint mobile devices such as 5G mobile terminals. Security analyses prove that the proposed scheme can prevent the information leakage. Experiment results guarantee that computation overhead of the proposed scheme in user side is low.