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A Fully decentralized framework for securely sharing digital content

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2019
Demir, Ahmet Serhat
Blockchain is a secure, immutable, and distributed public ledger that stores transactional data. It enables information transfer without the need for a trusted third party via its decentralized consensus mechanism. Besides finance, blockchain technology has the potential to change several industries, through smart contracts and decentralized applications. This thesis explores using blockchain technology, smart contracts, and Ethereum Web 3.0 stack for secure information and file sharing on a fully decentralized architecture. We aim to remove the need for a central authority in all layers of the application, and thus provide an alternative to the drawbacks of centralized content exchange platforms. Accordingly, a proof-of-concept decentralized application is designed. This design is implemented in the Ethereum ecosystem using blockchain for the immutable distributed ledger, Ether for cash transfers, and smart contracts for application logic. Since data storage in blockchain is expensive, Swarm is used as a decentralized reliable content storage system. Nevertheless, permissionless systems in the Ethereum ecosystem lack necessary data privacy, which causes risk for secure information exchange. In order to provide access control for sensitive content delivery without the need for a pre-shared secret, public key encryption is used. Also, to enable fair exchange between separate untrusted rational parties, a double escrow functionality is implemented as a model of fairness via incentive with deposit penalties. According to the validation and evaluation of our proof-of-concept, we show that Ethereum Web 3.0 stack is applicable to securely sharing and exchanging digital content without relying on a trusted third party.