U.S. cryptocurrency exchange Coinbase said on Thursday that hackers had stolen customer data and demanded $20 million to prevent public disclosure. Coinbase said the hackers' demands were made on Monday. The company said in a statement that the hackers' goal was to collect a list of customers who could be contacted while pretending to be Coinbase and tricking customers into handing over cryptocurrency. The company rejected the hackers' $20 million extortion. Coinbase also said it would compensate customers who were deceived into sending money to the attackers, and the amount of compensation could be between $180 million and $400 million.