Proofs of ownership in remote storage systems

Abstract

Cloud storage systems are becoming increasingly popular. A promising technology that keeps their cost down is deduplication, which stores only a single copy of repeating data. Client-side deduplication attempts to identify deduplication opportunities already at the client and save the bandwidth of uploading copies of existing files to the server.In this work we identify attacks that exploit client-side deduplication, allowing an attacker to gain access to arbitrary-size files of other users based on a very small hash signatures of these files. More specifically, an attacker who knows the hash signature of a file can convince the storage service that it owns that file, hence the server lets the attacker download the entire file. (In parallel to our work, a subset of these attacks were recently introduced in the wild with respect to the Dropbox file synchronization service.)To overcome such attacks, we introduce the notion of proofs-ofownership (PoWs), which lets a client efficiently prove to a server that that the client holds a file, rather than just some short information about it. We formalize the concept of proof-of-ownership, under rigorous security definitions, and rigorous efficiency requirements of Petabyte scale storage systems. We then present solutions based on Merkle trees and specific encodings, and analyze their security. We implemented one variant of the scheme. Our performance measurements indicate that the scheme incurs only a small overhead compared to naive client-side deduplication.

A Survey on Privacy Preserving in Authentication Protocol for Shared Authority Based Cloud Computing

“…Markov chain representations are used to find statistics on the number of iterations required, and computer algebra gives closed form results for the completion rates. S. Halevi, D. Harnik, B. Pinkas, and A. Shulman-Peleg [9] introduce the notion of proofs-of ownership (PoWs), which lets a client efficiently prove to a server that that the client holds a file, rather than just some short information about it. Merkle trees and specific encodings, and analyze their security.…”

Secure deduplication storage systems supporting keyword search

“…To prevent the adversary from launching these attacks, a new concept of Proof of Ownership (PoW) has been proposed [19], which enables users to prove their ownership of data copies to the storage server. PoW is implemented as an interactive algorithm.…”

“…As a result, the adversary can share these short values with other users and realize the content distribution attack. To prevent these attacks, Halevi et al [19] proposed the notion of "proofs of ownership" (PoW) for deduplication systems, such that a client can efficiently prove to the cloud storage server that he owns a file without uploading the file itself. The technique is to use more entropy and longer proof to prevent the sharing.…”

“…The technique is to use more entropy and longer proof to prevent the sharing. Several PoW constructions based on the Merkle Hash Tree are proposed [19] to enable client-side deduplication, which include the bounded leakage setting. Pietro and Sorniotti [27] propose another efficient PoW scheme by choosing the projection of a file onto some randomly selected bit-positions as the file proof.…”

Managing Deduplicate Data at Client Side in Public Cloud Storage Environment

“…It is proposed for reduce bandwidth as well as minimum space required to upload the data. In this paper use the new cryptographic methodology for secure proof duplication ( [1], [2]). …”