Bitcoin Gold Hack Shows 51% Attack Is Real

Up until now a 51% attack on bitcoin was considered an impossibility. 

Increasingly, however, the attack, which involves a hacker gaining control of a majority of systems on bitcoin’s network and altering transactions on its blockchain, is becoming a plausible reality. The latest proof of this comes from bitcoin gold, a bitcoin fork which began trading on exchanges last year. According to a post on one of the cryptocurrency’s forums, the hacker is targeting exchanges that trade bitcoin gold. (See also: What Is Bitcoin Gold, Exactly?)

“We have been advising all exchanges to increase confirmations and carefully review large deposits,” Edward Iskra, BTG’s communications director, wrote. The hacker could attempt to double-spend stolen coins from an exchange by exchanging them into fiat currency or another crypto and using the same coins from his or her wallet to buy more crypto. The online publication Bitcoinist estimates that the hacker stole $18 million worth of…