Just to throw in a couple of possibly outlandish theories: 1. as others have said, they could be collecting the encrypted messages and then tried to decrypt them using quantum computing, the Chinese have been reportedly trying to do this for many years now. 2. with metadata and all the information from other sources, they could infer what the conversation is about without the need to decrypt it: if I visit a page (Fa…
can analyze receivers data or receivers contact trees data which is easier to access.
The number of free or paid data sources is daunting.