How MTProto 2.0 Works: A Plain-English Deep Dive
Understand exactly what happens when your phone connects to a Telegram MTProto proxy — packets, keys, obfuscation and all.
The big picture
When you tap a TGFast proxy link, your Telegram client opens a TCP socket to one of our edge servers. It sends a 64-byte initial packet that contains a randomized header (the "obfuscation envelope"), then begins exchanging encrypted MTProto frames. The proxy server decrypts only enough of the envelope to know which Telegram data centre to forward to (DC1, DC2, DC4 or DC5), then opens a second TCP socket to that data centre and starts shuffling packets between the two. It never sees your message contents — those remain encrypted with keys negotiated end-to-end between your client and Telegram.
The obfuscation envelope
The 64-byte initial packet is the secret sauce that lets MTProto evade DPI. Its first 56 bytes are random, the next 4 bytes encode the protocol identifier, and the last 4 bytes encode the data centre number — but the entire 64-byte block is encrypted with AES-CTR using a key derived from the secret string. To an observer it looks like 64 random bytes followed by an opaque encrypted stream. This is why TLS 1.3, Tor, OpenVPN and MTProto all "look the same" to a packet inspector — they are all blobs of high-entropy data.
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Open the fleetThe "ee" secret format
Modern MTProto secrets start with "dd" or "ee". The "dd" prefix selects standard obfuscation. The "ee" prefix selects "fake TLS" obfuscation, which makes the very first packet impersonate a TLS ClientHello to a configurable hostname. This is critical in countries that block any non-TLS protocol on port 443. TGFast supports both variants — by default we issue "dd" secrets, but you can request "ee" secrets if your network actively interferes with non-TLS handshakes.
Key derivation and forward secrecy
After the initial handshake, the client and server perform a Diffie-Hellman key exchange to derive a fresh AES-256-IGE key for each session. IGE (Infinite Garble Extension) is an old block cipher mode chosen for its self-synchronising properties. Combined with daily key rotation, MTProto provides reasonable forward secrecy: even if an adversary records the entire stream and later compromises the long-term server key, they still cannot decrypt the past traffic.
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Join Telegram ChannelHow the proxy fits in
Importantly, an MTProto proxy is dumb — it never participates in the key exchange. It only inspects the obfuscation envelope to learn the target data centre, then blindly forwards encrypted frames in both directions. This is what makes proxy hosting trivially safe: a malicious proxy operator cannot read your messages even if they want to, because the cryptographic session is between you and Telegram's data centre, not between you and the proxy.
Performance characteristics
MTProto is unusually efficient compared to general-purpose VPNs. Per-packet overhead is about 32 bytes (vs. 80+ for OpenVPN, 56 for WireGuard). The protocol uses long-lived TCP connections with optional WebSocket framing, which keeps mobile radios in a low-power state. Telegram's servers also implement aggressive request batching, which is why "Telegram feels fast" even on poor networks — the proxy preserves these optimisations.
What MTProto cannot do
MTProto is built for Telegram and Telegram only. It cannot proxy your browser, your mail or any other app. If you need a general tunnel for the whole device, use a real VPN. MTProto also offers no IP-rotation: every packet you send appears to come from the proxy server's IP, so your "exit IP" is the proxy IP. This is an advantage for Telegram (looks like residential traffic) but a non-feature if you wanted to hop between many exits.
How DPI systems try to detect and block MTProto
Deep packet inspection (DPI) hardware used by national ISPs attempts to fingerprint MTProto traffic in three main ways. Port-based blocking: Telegram uses ports 443, 80 and 5222 by default. TGFast uses high-numbered ports (30 000–60 000) to avoid these. Entropy analysis: MTProto's obfuscated stream has near-maximum Shannon entropy (≈8 bits/byte), which DPI flags as "likely proxy or VPN". The "ee" Fake-TLS obfuscation defeats this by making the stream open with a recognisable TLS ClientHello that has normal entropy patterns. Timing fingerprinting: MTProto sessions have characteristic keep-alive intervals. TGFast introduces randomised jitter to the keep-alive schedule, defeating timing-based classification. Iran and China are the most advanced users of all three techniques; TGFast is tuned specifically against each.
MTProto vs other circumvention protocols: technical comparison
Compared to WireGuard: MTProto has less per-packet overhead (32 bytes vs 56 bytes) but is Telegram-only; WireGuard tunnels all traffic. Compared to TLS/HTTPS: MTProto's obfuscation layer is simpler but more resistant to DPI because it lacks TLS's predictable handshake record structure; with "ee" obfuscation it mimics TLS and becomes indistinguishable. Compared to Shadowsocks: Shadowsocks can carry any TCP traffic, but its byte stream is actively targeted by DPI databases in China and Iran; MTProto "ee" currently survives significantly longer in both countries. Compared to V2Ray with Reality: Reality provides the strongest GFW resistance but requires a rented VPS and complex configuration; MTProto is zero-setup and free.
The future: MTProto on QUIC and beyond
Telegram's engineering team has discussed moving MTProto to QUIC (UDP-based), which would enable 0-RTT connection resumption and reduce the latency of the first few packets in each session — particularly valuable in high-packet-loss networks like Irancell mobile. Open-source communities are also proposing "REALITY-style" domain fronting for MTProto, which would use real TLS certificates from major cloud providers rather than just mimicking the handshake. TGFast is testing both approaches in staging infrastructure. When production-ready improvements ship, they will roll out to all proxy cards automatically — no action required from users.