Authoritarian governments worldwide are increasingly using financial repression to disable their challengers. By surveilling and freezing bank accounts, they can stop democratic opposition in its tracks. At the same time, human rights groups from Nigeria to Russia to Hong Kong are turning to Bitcoin—a censorship-resistant digital currency that can be used without tying one's transactions to one's personal information—to receive donations, run payroll, and keep their operations going, even if dictators want them to stop.