Blog post by crypto professor Matthew Green, discussing what Telegram does (I wasn’t familiar with it) and criticizing its cryptography. He says Telegram by default is not end-to-end encrypted. It does have an end-to-end “secret chat” feature, but it’s a nuisance to activate and only works for two-person chats (not groups) where both people are online when the chat starts.
It still isn’t clear to me why Telegram’s founder was arrested. Green expresses some concern over that but doesn’t give any details that weren’t in the headlines.
I think you missed the point there. The value for the NSA is in knowing which phone numbers communicate with other phone numbers which is precisely the metadata that Signal leaks. This allows you to build networks of users who are doing private communication. Next, you can cross reference the phone numbers with the data from Google, Meta, etc. and then if you see that one of them is a person of interest, then you immediately know the other people they talk to who are now also of interest.
The fact that people keep trying to downplay this is truly phenomenal to me. Once again, Signal is an app that uses a central server based in the US, that almost certainly shares data with the government. Anybody who minimally cares about their privacy should be concerned about this.
Signal is not an app that’s private. Period. If you don’t understand this then you don’t understand what the term privacy means.