Ethereum Classic, the cryptocurrency created after the main Ethereum developers led by Ethereum founder Vitalik Buterin split off in a June 2016 hard fork to reverse the theft of $55 million in coins, suffered another loss this week. On Jan. 5, a miner or group of miners managed to gain control of more than half of the Ethereum Classic mining power, or hashrate, in what is called a “51% attack.” This gave them the ability to double spend ETC coins—basically spending a newly created coin and then forking the ETC blockchain, allowing them to cancel the transaction and be able to spend that coin again. Called a deep chain reorganization,…
When a 51% attack happens, a bunch of 0s and 1s don't suddenly shout "51% ATTACK" in red (via Shutterstock).