In the world of proof-of-work based blockchains, no security threat looms larger than the 51% attack. This has long been the greatest worry for the security of Bitcoin’s network, where no hacking event has posed any considerable risk to date. Naturally, those blockchains which adopt some variant of Bitcoin’s pioneered proof-of-work consensus algorithm must also reckon with this potential, and successful 51% attacks in altcoins have demonstrated that it is far from just a hypothetical scenario. In this article, we take a deeper look at the nature of 51% attacks, how they have manifested in reality, the scenario by which Bitcoin could be breached, and finally a simple question: would a 51% attack on Bitcoin be worth it?
What is a 51% Attack?