Distributed Storage with Strong Data Integrity based on Blockchain Mechanisms

Abstract

A blockchain is a datastructure that is an append-only chain of blocks. Each\nblock contains a set of transaction and has a cryptographic link back to\nits predecessor. The cryptographic link serves to protect the integrity of\nthe blockchain. A key property of blockchain systems is that it allows mu-\ntually distrusting entities to reach consensus over a unique order in which\ntransactions are appended. The most common usage of blockchains is in\ncryptocurrencies such as Bitcoin.\nIn this thesis we use blockchain technology to design a scalable architec-\nture for a storage system that can provide strong data integrity and ensure the\npermanent availability of the data. We study recent literature in blockchain\nand cryptography to identify the desired characteristics of such a system. In\ncomparison to similar systems, we are able to gain increased performance by\ndesigning ours around a permissioned blockchain, allowing only a predefined\nset of nodes to write to the ledger. A prototype of the system is built on top\nof existing open-source software. An experimental evaluation using different\nquorum sizes of the prototype is also presented.