Proof of Delivery of Digital Assets Using Blockchain and Smart Contracts

There is an immense need of a proof of delivery (PoD) of today's digital media and content, especially those that are subject to payment. Current PoD systems are mostly centralized and heavily dependent on a trusted third party (TTP) especially for payment. Such existing PoD systems often lack security, transparency, and visibility, and are not highly credible, as the TTP can be subject to failure, manipulation, corruption, compromise, and hacking. In this paper, we propose a decentralized PoD solution for PoD of digital assets. Our solution leverages key features of blockchain and Ethereum smart contracts to provide immutable and tamper-proof logs, accountability, and traceability. Ethereum smart contracts are used to orchestrate and govern all interactions and transactions including automatic payments in Ether cryptocurrency between customers, digital-content provider, and the file server hosting the digital content. All entities are incentivized to act honestly, and our solution has a mechanism to handle dispute if arisen among participants. The solution has an off-chain secure download phase involving the file server and customers. Moreover, our solution leverages the benefits of interplanetary file system to store the agreed upon terms and conditions between the smart contract actors. A security analysis of our proposed system has been provided. The full code of the smart contract has been publicly made available on Github.