Hierarchy attribute-based encryption with timing enabled privacy preserving keyword search mechanism for e-health clouds

Electronic Health Record (EHR) has added great ease in health care systems. Sensitive data in EHR requires a highly secured system. The traditional systems enable the information clients to search and decrypt the encrypted data in a limited duration of time but have not addressed the characteristic of multilevel hierarchy structure of data sharing in EHR files. In this paper an innovative method, hierarchy attribute-based encryption with timing enabled privacy preserving keyword search mechanism for e-health clouds is proposed. This proposed method adopts a Hierarchy Attribute Based Encryption with keyword search scheme (HABE-KS), where it encrypts the hierarchical EHR files by combining the layered access structures into a single access structure. By incorporating timing enabled proxy reencryption function, the information clients will be consequently denied to, access and look after the data after a predefined span of time which is provided by the information owner. Therefore, information clients performs keyword search over the encrypted data if the access policy is satisfied and within the specified time duration provided by information owner. Thus, this proposed method guarantees confidentiality while keeping up a fine grained access control and versatile client revocation. Moreover, the proposed scheme is proved to be more secure in the standard model. The proposed scheme is highly efficient and the experimental results shows the storage cost and encryption time cost comparison of multiple ciphertext files.