Let's see, what does the article say? - Telegram isn't end-to-end encrypted per default: true - Telegram uses homebrew encryption (MTproto): true - Telegram

Let's see, what does the article say? - Telegram isn't end-to-end encrypted per default: true - Telegram uses homebrew encryption (MTproto): true - Telegram presence information, at one point, could be read by someone who isn't your contact: true