nsa.gov

QNZjk TIL that in World War 2 Nazis used secret codes to communicate using a machine called the Enigma Machine which would use morse code but make it very, very difficult and there was a building in England where many people were recruited to work as decoders and it would take hours or days to solve.
GApKG TIL about Project Venona, the US effort to decrypt KGB/GRU intercepts leading to some of the greatest intelligence breakthroughs during the cold war. Including exposing critical Soviet assets, (ie. the Rosenbergs, David Greenglass, and Kim Philby)