bitcoin is that you don’t need to trust the people to whom you send or receive money, because the software makes it technically impossible for anyone to cheat the system. Instead of relying on humans and their flawed judgment, you rely on the laws of mathematics. But a recent attack on the cryptocurrency Ethereum Classic—not to be confused with the original Ethereum project—shows once again how hard it is to remove human frailty from digital systems.

Like other cryptocurrencies, Ethereum Classic relies on a decentralized ledger known as a blockchain created and shared by the machines that process transactions on the network. This ledger ensures that no one can spend their virtual tokens twice. Unless, that is, someone could take over at least 51 percent of the machines in the network. That’s what appears to have happened last weekend.

Currency exchange Coinbase said Monday it had detected double spends on the Ethereum Classic platform on Saturday and that it had suspended transactions involving Ethereum Classic. Kraken, another exchange, followed suit with a similar announcement. Coinbase security engineer Mark Nesbitt wrote in a blog post that the company had spotted 12 instances of double spending Ethereum Classic tokens, involving a total value of about $1.1 million.¹Ethereum Classic is not as popular as some other cryptocurrencies: It had a total market value of $553.5 million on Friday, according to CoinMarketCap; by comparison, ether, the currency created by the original Ethereum project, had a value of $16.3 billion, and bitcoin a value of $67.5 billion.

Nesbitt told WIRED that Coinbase is “very confident” that the d

Read More