Secure proof of ownership for deduplicated cloud storage system
Jay A. Dave, Meghna Bhatt, Deep Pancholi · International Journal of Information and Computer Security · 2023
Deduplication is a popular data reduction technique that minimises storage and communication costs. However, in a deduplicated system, an adversary can obtain access to the entire file on the server by showing just hash of file. A standard solution is that the server sends a file-based challenge to verify the client's file-ownership. Unfortunately, in the state-of-the-art schemes, adversary can correctly respond to the challenge with knowledge of the hash of file-blocks, where |Hash(blocks)| < < |File|. In this paper, we propose a secure proof of ownership scheme. In our proposal, the server randomly selects a set of file-blocks as a challenge. Therefore, if the client knows the complete file, he can correctly respond and get file access. We derive lower bound for no. of blocks in challenge. We prove that adversary cannot get success by learning former challenges-responses. We implement our approach in a realistic environment and compare performance with the state-of-the-art schemes.