Cryptology ePrint Archive: Report 2013/429

DupLESS: Server-Aided Encryption for Deduplicated Storage

Mihir Bellare and Sriram Keelveedhi and Thomas Ristenpart

Abstract: Cloud storage service providers such as Dropbox, Mozy, and others perform deduplication to save space by only storing one copy of each file uploaded. Should clients conventionally encrypt their files, however, savings are lost. Message-locked encryption (the most prominent manifestation of which is convergent encryption) resolves this tension. However it is inherently subject to brute-force attacks that can recover files falling into a known set. We propose an architecture that provides secure deduplicated storage resisting brute-force attacks, and realize it in a system called DupLESS. In DupLESS, clients encrypt under message-based keys obtained from a key-server via an oblivious PRF protocol. It enables clients to store encrypted data with an existing service, have the service perform deduplication on their behalf, and yet achieves strong confidentiality guarantees. We show that encryption for deduplicated storage can achieve performance and space savings close to that of using the storage service with plaintext data.

Category / Keywords: storage, deduplication, message-locked encryption, convergent encryption

Publication Info: Usenix Security Symposium 2013

Date: received 2 Jul 2013

Contact author: sriramkr at cs ucsd edu

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Version: 20130703:081728 (All versions of this report)

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