Patient medical data are stored as Electronic Health Records (EHRs) in the cloud for decentralized clinical access. Information related to a patient’s health, diagnosis, and medication is vital for which individual privacy and security are vital considerations. This article introduces a Two-Phased Privacy Preserving Security Scheme (TP3SS) for EHR stored in clouds. The proposed scheme offers secure access control and attribute-based encryption for privacy-preserving and preventing data falsification. Secure access control is achieved by establishing mutual key-dependent smart contracts between the user, doctors and the EHR storage. The key authentication is provided using record-related attribute encryption that is valid within the contract period. The access and key validity are confined to the smart contract allocated interval by verifying the user identity. Here validity verification and access confinement are pursued using ledge-stored user information. The validation occurs for ensuring the EHR and user attributes are mapped together in the current and previous smart contract access sessions. In the record management process, Hyperledger fabric blockchain is used for preventing internal computation complexities. Similarly, the attribute that is inferred by the Hyperledger fabric blockchain in the current access session is alone used for a key generation; used for accessing and sharing the records. This process prevents the entry of adversary access and improves the security level under controlled complexity.

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