Meta-Key: A Secure Data-Sharing Protocol under Blockchain-Based Decentralised Storage Architecture

In this paper a secure data-sharing protocol under blockchain-based decentralised storage architecture is proposed, which fulfils users who need to share their encrypted data on-cloud. It implements a remote data-sharing mechanism that enables data owners to share their encrypted data to other users without revealing the original key. Nor do they have to download on-cloud data with re-encryption and re-uploading. Data security as well as efficiency are ensured by symmetric encryption, whose keys are encrypted by user's public key. Then, the key-ciphertext is recorded into a blockchain system so reliability and secrecy are ensured. When data are necessary to be shared, proxy re-encryption is adopted in order to generate new symmetric keys as well as corresponding ciphertexts dedicated for data-sharing so security of user's original key can be well-remained.