Blockchain based secure medical data outsourcing with data deduplication in cloud environment

With the rapid growth of cloud computing, an increasing number of individuals and businesses are opting to store their vast data on the cloud in order to cut data maintenance costs and obtain more easy access. The cloud-based Electronic Health Records (EHR) sharing scheme has provided many benefits in recent years, but the centralization of the cloud raises challenges to privacy protection and data security. Blockchain technology is viewed as a possible solution to these challenges because of its unique properties of unforgeability, anonymity, and verifiability. Therefore, a blockchain based secure data outsourcing scheme is proposed in this paper. In the proposed scheme, each activity on outsourcing EHRs is recorded as a transaction on the public blockchain, authenticity is ensured by registration, and secure data access is ensured by keyword search. Initially, the EHR is encrypted by the proposed Enhanced Map Chaotic Encryption (EMCE) algorithm to ensure confidentiality. Then, data de-duplication is performed by the proposed Tri-Level Chunk Hashing (TL-CH) technique to eliminated duplicate records and reduce the storage space. Finally, the integrity of outsourced EHRs is validated by the Third-Party Auditor (TPA). The performance and security analysis show that the proposed scheme can provide solid security against various attacks, and the storage space is reduced.