The intelligence coup of the century: For decades, the CIA read the encrypted communications of allies and adversaries.

The Swiss firm made millions of dollars selling equipment to more than 120 countries well into the 21st century. Its clients included Iran, military juntas in Latin America, nuclear rivals India and Pakistan, and even the Vatican.

But what none of its customers ever knew was that Crypto AG was secretly owned by the CIA in a highly classified partnership with West German intelligence. These spy agencies rigged the company’s devices so they could easily break the codes that countries used to send encrypted messages.

The decades-long arrangement, among the most closely guarded secrets of the Cold War, is laid bare in a classified, comprehensive CIA history of the operation obtained by The Washington Post and ZDF, a German public broadcaster, in a joint reporting project. —Washington Post