  In this paper, we describe LUNES-Blockchain, an agent-based simulator of
blockchains that is able to exploit Parallel and Distributed Simulation (PADS)
techniques to offer a high level of scalability. To assess the preliminary
implementation of our simulator, we provide a simplified modelling of the
Bitcoin protocol and we study the effect of a security attack on the consensus
protocol in which a set of malicious nodes implements a filtering denial of
service (i.e. Sybil Attack). The results confirm the viability of the
agent-based modelling of blockchains implemented by means of PADS.
