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. He adds: "Telegram has become my primary news source." But because group chats and the channel features are not end-to-end encrypted, Galperin said user privacy is potentially under threat. Although some channels have been removed, the curation process is considered opaque and insufficient by analysts. 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.
from fr
