سلام,
گویا تلگرام از لایه های امنیتی خیلی خوبی برخورداره, میتونید خودتون بررسی کنید.
Telegram
Telegram is a relative newcomer to the mobile messaging scene and as WhatsApp recently suffered from an outage, Telegram's user base benefited adding a few million users during the weekend. It was a lucky break for the service, which has been pitching itself as a safer alternative to WhatsApp all along, citing stronger encryption and a decentralized infrastructure with data centers in different jurisdictions. The company is so confident in its claims that they're currently running a challenge offering $200,000 to the hacker who can break Telegram.
The service supports two layers of secure encryption: server-client for regular chats and client-client for 'secret' chats. Both use 256-bit symmetric AES encryption, RSA 2048 encryption and Diffie–Hellman secure key exchange. The main difference is that regular chats -- including messages, photos, videos and documents -- are kept on their servers so you can access them at any time from any device. In secret chats on the other hand all messages are erased as soon as they are delivered and no logs are kept by Telegram. For the same reasons secret chats are not available in the cloud, you can only access those messages from the device they were sent to or from, while an optional self-destruct feature ensures they disappear from participating devices as well after a set time.