A secure authorized deduplication scheme for cloud data based on blockchain

Deduplication scheme based on convergent encryption (CE) is widely-used in cloud storage system to eliminate redundant data. However, the adversaries can obtain the data by the brute-force attack, if the data belongs to a predictable set for CE. In addition, previous works usually introduce the third-party auditors to execute the data integrity verification, suffering from data disclosure by the auditors. In this paper, we propose a secure authorized deduplication scheme based on blockchain, which can ensure the confidentiality and security of the users' data stored on cloud servers. In our scheme, the users can utilize the smart contract to create a tamper-proofing ledger, which can protect the data from illegal modification. Meanwhile, the users can execute the integrity audit protocols to check the users’ data integrity by the smart contract. Moreover, a hierarchical role hash tree (HRHT) will be constructed to create the role key when the users upload their data to CSP, allowing the authorized users to access the data. Security analysis and performance evaluation demonstrate that our proposed scheme is resilient against the brute-force attack and the collusion attack, while it has limited computation overhead.