> Years before, the government had placed encryption, a method for scrambling messages so they can only be understood by their intended recipients, on the United States Munitions List, alongside bombs and flamethrowers, as a weapon to be regulated for national security purposes. Companies and individuals exporting items on the munitions list, including software with encryption capabilities, had to obtain prior State Department approval.
— Electronic Frontier Foundation: EFF's History
Before that, export rules could be "worked around" by printing cryptography in books.
The United States had to be brought to court to finally allow cryptography: https://en.m.wikipedia.org/wiki/Bernstein_v._United_States
> Years before, the government had placed encryption, a method for scrambling messages so they can only be understood by their intended recipients, on the United States Munitions List, alongside bombs and flamethrowers, as a weapon to be regulated for national security purposes. Companies and individuals exporting items on the munitions list, including software with encryption capabilities, had to obtain prior State Department approval. — Electronic Frontier Foundation: EFF's History
Before that, export rules could be "worked around" by printing cryptography in books.
See also https://en.m.wikipedia.org/wiki/Export_of_cryptography_from_...