Abstract
We develop EthernityDB, a system that integrates database functionality into an Ethereum blockchain. In contrast to other systems, in our approach all the data is kept on the chain, giving us all the guarantees of a blockchain in terms of consistency, immutability, and security. Mapping the database functionality onto Ethereum’s smart contracts is not a straightforward process: by modularizing the code in certain ways, we can bring down the transaction cost considerably. In a experimental evaluation we illustrate various trade-offs, measuring these transaction costs, and also discuss building blockchain-based data storage in a more general context.