What If Keys Are Leaked? towards Practical and Secure Re-Encryption in Deduplication-Based Cloud Storage

Weijing You,Lei Lei,Bo Chen,Limin Liu

doi:10.3390/info12040142

Abstract

By only storing a unique copy of duplicate data possessed by different data owners, deduplication can significantly reduce storage cost, and hence is used broadly in public clouds. When combining with confidentiality, deduplication will become problematic as encryption performed by different data owners may differentiate identical data which may then become not deduplicable. The Message-Locked Encryption (MLE) is thus utilized to derive the same encryption key for the identical data, by which the encrypted data are still deduplicable after being encrypted by different data owners. As keys may be leaked over time, re-encrypting outsourced data is of paramount importance to ensure continuous confidentiality, which, however, has not been well addressed in the literature. In this paper, we design SEDER, a SEcure client-side Deduplication system enabling Efficient Re-encryption for cloud storage by (1) leveraging all-or-nothing transform (AONT), (2) designing a new delegated re-encryption (DRE), and (3) proposing a new proof of ownership scheme for encrypted cloud data (PoWC). Security analysis and experimental evaluation validate security and efficiency of SEDER, respectively.

Highlights

Cloud storage services are widely deployed nowadays
We evaluate the performance of SEDER in different phases
For the Update phase, we compare the performance of our re-encryption process (i.e., delegated re-encryption (DRE)) with that in REED [15], which consumes much less bandwidth and computational resources compared to the existing re-encryption designs in [17,18,41] by taking full advantage of all-or-nothing transform (AONT), but completely relies on the client for the re-encryption process due to the nature of the server-side deduplication

Summary

Introduction

Cloud storage services are widely deployed nowadays. Popular services include Amazon S3 [1], Apple iCloud [2], and Microsoft Azure [3]. Data owners pay for storage they use, eliminating expensive costs of maintaining dedicated infrastructures. As more and more users turn to public clouds for storage, the amount of data stored in clouds grows rapidly. The clouds store what have been sent by the data owners. This will lead to a significant waste of storage space, as different data owners may upload identical data. A remediation is to perform deduplication, in which clouds only store a unique copy of duplicate data from different data owners to reduce unnecessary waste of storage space. Research from Microsoft [4]

Methods

Results

Discussion

Conclusion