EHRChain: A Blockchain Based EHR System Using Attribute Based and Homomorphic Cryptosystem

Abstract: The medical industry urgently needs to address issues such as secure storage, reliable sharing, access control and privacy protection. In this article, we propose EHRChain, a blockchain-based EHR system that uses an attribute-based homomorphic cryptosystem to solve the aforementioned problems. First, we designed a medical record storage solution based on blockchain and IPFS technology to achieve secure large-capacity medical data storage and reliable sharing. Second, we proposed an improved cryptographic primitive called SHDPCPC-CP-ABE. Our SHDPCPC-CP-ABE simultaneously realizes the functions of partially concealing ciphertext-based semi-policy and dynamic authority change. In addition, our regime achieves subject neutrality of forensic identification of medical disputes and fine-grained access control to medical data. Third, our system applies an additional homomorphic cryptosystem, the Paillier cryptosystem, with optimized parameters to protect patient privacy during the medical insurance claim process. Index Terms: Ethereum, Blockchain, EHRchain, Healthcare