Privacy Preserving Attribute-Based Encryption with Conjunctive Keyword Search for E-health Records in Cloud

The advent of cloud computing in the healthcare system makes accuracy and speed increased, costs reduced, and health services widely used. However, system users are always seriously concerned about the security of outsourced data. The ciphertext-policy attribute-based encryption (CP-ABE) is a promising way to ensure the security of and facilitate access control over outsourced data. However, conventional CP-ABE schemes have security aws such as lack of attribute privacy and resistance to the keywords guessing attacks as well as the disability to multi-keyword searches. To meet such shortcomings, we present a scheme supporting multi-keyword search and ne-grained access control, simultaneously. The proposed scheme is resistant to the o ine keywords guessing attack. Privacy-preserving in the access structure is another feature of the proposed scheme. The security analysis indicates that our scheme is selectively secure in the standard model. Finally, the performance evaluation of the proposed scheme shows the e ciency is reasonable despite the added functionalities.