A blockchain-based compact audit-enabled deduplication in decentralized storage

Abstract

Secure deduplication and data auditing are significant in improving the resource utilization and data integrity protection of data outsourcing services. However, existing audit-enabled deduplication schemes cannot implement block-level deduplication over audit tags since they contain file information, and have to bear the consequent storage burden. Also, they suffer from the low coupling problem caused by the difference in optimal data chunking between deduplication and auditing. In this paper, we propose a blockchain-based compact audit-enabled deduplication scheme in decentralized storage. Specifically, we introduce the concept of N-ary tag commitment tree (NTCT), which integrates the information of all data blocks into a file authenticator to support integrity verification and enable block-level deduplication over audit tags. On this basis, we propose a blockchain-based compact audit-enabled deduplication protocol, which adopts an aggregatable vector commitment to generate audit tags, thereby overcoming the low coupling problem between deduplication and auditing. Notably, data users can outsource the task of tag generation to storage servers. Meanwhile, the capabilities of duplication detection, proof of ownership (PoW), and integrity verification are integrated into audit tags to reduce tag redundancy. Furthermore, we present an update protocol to allow data users to achieve a lightweight data update without uploading the entire new data. Finally, security analysis and performance evaluation demonstrate that our scheme is practical.