The use of IoT technology in collecting personal health records (PHR) within the eHealth environment is a growing trend. However, data integrity is a concern as cloud service providers (CSPs) often cannot guarantee it. Blockchain technology offers a solution to guarantee data integrity and traceability. However, the immutability of traditional blockchain conflicts with GDPR's requirements. To address scalability and privacy concerns, we have designed a comprehensive scheme that integrates the redactable blockchain with the existing revocable IPFS mechanism. Our scheme overcomes the disadvantage of residual downloading information in the traditional blockchain. Additionally, we have developed an enhanced proxy re-encryption scheme that simplifies access control for physicians without the need for complex group key management. Unlike traditional blockchains and P2P file sharing systems, our PHR platform allows for selective removal of records and files while maintaining auditable logs. Evaluation results demonstrate that our proposed scheme effectively enhances the exclusive revocation feature with acceptable overheads. To the best of our knowledge, this is the first work to provide the merit of fully complete record and file revocation on a blockchain-based system.

With the rapid growth of blockchain, more and more people possess cryptocurrencies or use decentralized applications (Dapp). A wallet in blockchain not only stores your assets but also represents your online identity. Nowadays, document notary using blockchain is getting mature to prevent the problem of the counterfeit certificate. In this paper, we integrate a cellphone-based wallet with a novel visional certificate verification system. By the trusted execution environment (TEE) protection, a user can isolate his/her private key without the leakage attack. Two-factor authentication is required to generate a signature. Different from existing platforms, our system adopts IPFS, a P2P network for storing and sharing data, for storing the certificate image, which offers the function of visional verification for better persuasiveness. Furthermore, the unique time-limited verification can restrict the accessing period of the verifier for better privacy protection. As a result, our verification system provides several promising features to enhance security and privacy strength.