A blockchain based secure and privacy aware medical data sharing using smart contract and encryption scheme

With the rapid progress of network information technologies, security in medical data transmission has emerged as a popular research topic. Electronic Health Data (EHR) is vulnerable to security breaches, tampering, manipulation, and data leakage. The blockchain's data integrity, decentralization, and anonymity opened up new possibilities for addressing the aforementioned issues. Therefore, this paper presents a Blockchain-based Access Control Scheme (BACS) with Multiple Party Authority (MPA), smart contract, and proxy re encryption to secure the EHR. The proposed scheme consists of six phases: the registration phase, appointment phase, data aggregation stage, storage phase, query phase, and validation phase. The medical data is encrypted by using a Lightweight Fused Cryptographic (LFC) algorithm with the signature of the patient and doctor to ensure confidentiality and integrity. The encrypted EHR is then stored on Interplanetary File Systems (IPFS), which is a decentralised file storage platform. Moreover, the developed smart contract verifies the authenticity of the users, provides a reputation score for the oracle, and creates a time seal. This enhances the security of the system from external attacks as well as internal attacks. A security analysis is conducted for the proposed method, and the performance is compared with the existing techniques based on encryption time, decryption time, and computation cost.