Protecting Digital Currency Transactions on Bitcoin Networks Against Delay-Based Attacks*

Bitcoin (₿) synchronizes a public ledger over a large decentralized blockchain network as an underlying infrastructure. Propagation delay among long chains of network nodes is a major threat to message dissemination and integrity of digital currency transactions. In this paper, a comprehensive study presents state-of-the-art protection methods of digital currency transactions against security threats caused by the propagation delay on the Bitcoin network. We discuss the network propagation algorithms and illustrate the main factors affecting the propagation delay and the major security attacks threatening digital currency transactions on these networks. Based on these factors, we describe and compare the possible countermeasures for securing the Bitcoin network against the major threats.