MTProto: Telegram mobile protocol

Last updated: April 2026

Protocol overview

MTProto is Telegram's cryptographic transport protocol designed for secure and reliable delivery in unstable mobile networks.

It provides confidentiality, integrity, and endpoint authentication while remaining lightweight enough for high-latency connections.

MTProto 2.0 replaces SHA-1 with SHA-256, improves key derivation, and adds randomized padding to reduce traffic fingerprinting.

Term	Description
`auth_key`	Long-term authorization key negotiated during client-server handshake.
`msg_key`	Message key derived from payload hash and part of auth_key.
`server_salt`	Temporary 64-bit salt used to protect against replay attacks.
`session_id`	Session identifier that binds messages to a specific client session.

Messages are encrypted with AES-256-IGE; the key and IV are derived from auth_key and msg_key.

The handshake is based on Diffie-Hellman with RSA key verification to prevent man-in-the-middle attacks.

Feature	MTProxy	VPN	SOCKS5
Scope	Telegram only	All traffic	Configured apps
Setup	One click	Client app + config	Manual setup
Traffic camouflage	FakeTLS/HTTPS	Protocol dependent	No

Telegram clients support MTProxy natively. Opening a tg://proxy link adds and enables the proxy in a few taps.

Using a secret with FakeTLS parameters helps disguise traffic as normal HTTPS and improves resilience against DPI blocking.