Telegram is fairly secure for the average user but has some notable privacy and security limitations. Its default chats are encrypted in transit but are stored decrypted on Telegram's servers, meaning end-to-end encryption (E2EE)—the strongest standard of privacy—is not enabled by default. To have true E2EE, users must manually enable "Secret Chats," which only apply to one- on-one conversations, while group chats and public channels are not end-to-end encrypted at all. This means Telegram theoretically could access your message content and might comply with governmental data requests. Telegram uses the MTProto protocol for encryption, which has been updated to a more secure version, but critiques remain due to the app's metadata collection practices and its default use of server-client encryption rather than universal E2EE. Users are also required to register with their phone number, which can be a privacy concern. In summary, Telegram offers decent security with caveats: it is safer than mass-market messengers in some respects but less secure than apps like Signal that provide E2EE by default. For maximum privacy, users must actively use secret chats, but even then, metadata like IP addresses and device information might be collected by Telegram.

Key Security Points of Telegram

• Default chats are server-client encrypted (not end-to-end encrypted).
• Secret chats provide true end-to-end encryption but must be manually enabled per conversation.
• Group chats and channels do not have end-to-end encryption.
• Telegram collects metadata including IP address and device details.
• Registration requires a phone number.
• Uses MTProto encryption protocol, with MTProto 2.0 being cryptographically secure.
• Potential vulnerabilities include phishing, malware risks due to lax content moderation, and possible government data requests handled by Telegram.

This makes Telegram a moderately secure platform if users take specific steps, but it is not fully secure by default like some other encrypted messaging apps.