# SIGSALY A classified speech encryption system developed by [[wiki/Bell Labs|Bell Labs]] during World War II, used for secure voice communications between Allied leaders including Roosevelt and Churchill. SIGSALY was one of the first applications of digital communications technology, predating the public digital revolution by decades. It exemplifies Bell Labs' deep integration with U.S. defense infrastructure, as documented in [[articles/Bell Labs and the Distributed Architecture of American Power|Bell Labs and the Distributed Architecture of American Power]].