BlockSim: Blockchain Simulator

A blockchain is a distributed ledger in which participants that do not fully trust each other agree on the ledger's content by running a consensus algorithm. This technology is raising a lot of interest both in academia and industry, but the lack of tools to evaluate design and implementation decisions may hamper fast progress. To address this issue, this paper presents a discrete-event simulator that is flexible enough to evaluate different blockchain implementations. These blockchains can be rapidly modeled and simulated by extending existing models. Running Bitcoin and Ethereum simulations allowed us to change conditions and answer different questions about their performance. For example, we concluded that doubling the number of transactions per block has a low impact on the block propagation delay (10ms) and that encrypting communication has a high impact in that delay (more than 25%).