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 oncloud. 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 & 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 reencryption 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.