RECAST: Random Entanglement for Censorship-Resistant Archival STorage

Barbi, Roberta; Burihabwa, Dorian; Felber, Pascal; Mercier, Hugues; Schiavoni, Valerio

doi:10.1109/dsn.2018.00029

Cited by 3 publications

(4 citation statements)

References 16 publications

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“…Essentially, we want the benefits of regular entanglement in a sliding window and the benefits of uniformly random entanglement. A prototype in this direction involves pointers selected using a half-normal distribution for quick forward integrity, combined with pointers chosen uniformly at random for good longterm protection [42]. The prototype also provides temporary replication for new documents and gets rid of the replicas as they age.…”

Section: Entanglement and Codingmentioning

confidence: 99%

STeP-Archival: Storage Integrity and Tamper Resistance Using Data Entanglement

Mercier

Augier

Lenstra

2018

IEEE Trans. Inform. Theory

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We present STEP-archives, a novel and practical data archival architecture, where an attacker who wants to censor or tamper with a data object must cause obvious collateral damage to a large number of other objects in the system. We use maximum distance separable erasure codes to entangle unrelated data blocks and provide redundancy against storage failures, which results in an archive with constant time read-write operations. We show a tradeoff for the attacker between attack complexity, irrecoverability, and collateral damage. We also show that the problem is asymmetric between attackers and defenders; while a defender can efficiently recover from imperfect attacks, an attacker must solve an NP-hard problem to find a perfect (irrecoverable) attack that minimizes collateral damage to other data objects, or even approximate its size. We then study efficient sample-heuristic attack algorithms that lead to irrecoverable but large damage and demonstrate how some strategies and parameter choices allow to resist these sample attacks. Finally, we provide empirical evidence that an attacker who wants to irrecoverably tamper with a document archived long enough must destroy a constant fraction of the archive.

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Section: Entanglement and Codingmentioning

confidence: 99%

STeP-Archival: Storage Integrity and Tamper Resistance Using Data Entanglement

Mercier

Augier

Lenstra

2018

IEEE Trans. Inform. Theory

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“…Finally, we look at how storage overhead can be tamed beyond with better compression gains than classic data reduction techniques without sacrificing on performance. [32,34,31] Chapter 4 First and fully functional implementation of STeP [17,141] Chapter 5 Implementation and evaluation of a framework for stackable user-space file systems [207,33] Chapter 6 Integration and evalution of a data deduplication scheme in user-space file system [183] 1.…”

Section: Taming Storage Overhead With Practical and Efficient Data Rementioning

confidence: 99%

“…• The introduction of Recast [17], a fully functional implementation of STeP [14], a coding scheme that blends erasure coding for redundancy and data entanglement for censorship detection. This work was led by Roberta Barbi under the supervision of Pascal Felber, Valerio Schiavoni and Hugues Mercier.…”

Section: Contributionsmentioning

confidence: 99%

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Erasure coding for distributed storage systems

Burihabwa¹

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Cloud storage has durably entered the stage as go-to solution for business and personal storage. Virtually extending storage capabilities to infinity, cloud storage enables companies and individuals to focus on content creation without fear of running out of space or losing data. But as users entrust more and more data to the cloud, they also have to accept a loss of control over the data they o˜oad to the cloud. At a time when online services seem to be making a significant part of their profits by exploiting customer data, concerns over privacy and integrity of said data naturally arise. Are their online documents read by the storage provider or its employees? Is the content of these documents shared with third party partners of the storage provider? What happens if the provider goes bankrupt? Whatever answer can be o˙ered by the storage provider, the loss of control should be cause for concern. But storage providers also have to worry about trust and reliability. As they build distributed solutions to accommodate their customers’ needs, these concerns of control extend to the infrastructure they operate on. Conciliating security, confidentiality, resilience and perform-ance over large sets of distributed storage nodes is a tricky balancing act. And even when a suitable balance can be found, it is often done at the expense of increased storage overhead. In this dissertation, we try to mitigate these issues by focusing on three aspects. First, we study solutions to empower users with flexible tooling ensuring security, integrity and redundancy in distributed storage settings. By leveraging public cloud storage o˙erings to build a configurable file system and storage middleware, we show that securing cloud-storage from the client-side is an e˙ective way maintaining control. Second, we build a distributed archive whose resilience goes beyond standard redundancy schemes. To achieve this, we implement Recast, relying on a data entanglement scheme, that encodes and distributes data over a set of storage nodes to ensure durability at a manageable cost. Finally, we look into o˙setting the increase in storage overhead by means of data reduction. This is made possible by the use of Generalised Deduplication, a scheme that improves over classical data deduplication by detecting similarities beyond exact matches.

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