In 1991, a programmer named Phil Zimmermann released a piece of software called Pretty Good Privacy. It let anyone encrypt a message so completely that no government, no corporation, no intelligence agency could read it without the key. He put it on the internet for free.

The United States government opened a criminal investigation.

The charge was arms trafficking.

Not metaphorically. Literally. The US State Department had classified strong encryption as a munition, in the same legal category as tanks, fighter jets, and missiles. Exporting it without a licence was a federal crime. Zimmermann had put PGP on a public server. People outside the US had downloaded it. As far as the government was concerned, he had shipped weapons across borders.