Telegram does offer end-to-end encrypted communications through Secret Chats, but this is not the default setting. Standard conversations use the MTProto method, enabling server-client encryption but with them stored on the server for ease-of-access. This makes using Telegram across multiple devices simple, but also means that the regular Telegram chats you’re having with folks are not as secure as you may believe. Also in the latest update is the ability for users to create a unique @username from the Settings page, providing others with an easy way to contact them via Search or their t.me/username link without sharing their phone number. Individual messages can be fully encrypted. But the user has to turn on that function. It's not automatic, as it is on Signal and WhatsApp. In a message on his Telegram channel recently recounting the episode, Durov wrote: "I lost my company and my home, but would do it again – without hesitation." "Your messages about the movement of the enemy through the official chatbot … bring new trophies every day," the government agency tweeted.
from it