> You seem to be implying that governments and three-letter agencies use some vastly superior cryptographic scheme

About a month ago there was a discussion here saying Signal is preinstalled and widely used at the CIA.

https://news.ycombinator.com/item?id=43478091

It's also recommended by the government's cybersecurity agency CISA.

https://www.cisa.gov/sites/default/files/2024-12/guidance-mo...