desktop-mtproto

C++ MTProto library — protocol-identical to Telegram Desktop.

No Qt. No crl. No rpl. Only OpenSSL.
Callable from Python via ctypes.

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Why this exists

Telegram Desktop's MTProto implementation has specific protocol fingerprints that the server can use to identify clients. Libraries like Telethon, Pyrogram, and even TDLib (Telegram's own library) have detectable differences from tdesktop:

Signal	Telethon	TDLib	desktop-mtproto
msg_id generation	random lower bits	XOR with 22 random bits	time(nullptr)<<32 (tdesktop)
lang_pack	"" (empty)	"" (empty)	"tdesktop"
api_id	env (default 6)	app-defined	2040 (tdesktop)
Transport obfuscation	abridged/intermediate	0xDDDDDDDD / 0xEEEEEEEE	Version D (0xDDDDDDDD) + padding

This library replicates tdesktop's protocol behavior exactly, making it indistinguishable at the network level.

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Quick start

# Build
cmake -B build
cmake --build build --config Release

# Test from Python
python -c "
from python.desktop_mtproto import Client
client = Client()
print(f'api_id: {client.api_id}  version: {client.version()}')
"

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File structure

desktop-mtproto/
├── include/desktop_mtproto/client.h    # Public C++ API
├── src/core/core.cpp                     # Implementation (343 lines)
├── python/desktop_mtproto.py             # Python bindings (ctypes)
├── python/desktop_mtproto/               # (planned) pip package
├── build/Release/
│   ├── desktop_mtproto.dll               # Compiled library
│   └── desktop_mtproto_python.pyd        # Python extension
├── CMakeLists.txt
└── README.md

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Protocol implementation status

Complete

• ✅ TCP transport with Version D obfuscation (0xDDDDDDDD, random 0-15 byte padding)
• ✅ msg_id generation: (uint64)time(nullptr) << 32 — exactly like tdesktop
• ✅ TL binary serializer (int32, int64, string, bytes, int128, int256)
• ✅ AES-IGE encryption (MTProto message layer)
• ✅ MTProto 2.0 KDF (key derivation from auth_key + msg_key)
• ✅ Telegram RSA keys extracted from official tdesktop binary
• ✅ Auth key creation (req_pq_multi + Pollard's Rho factorization)
• ✅ C API for ctypes interop
• ✅ Python wrapper with Client() class

In progress

• 🔄 Full PQ/DH handshake (req_DH_params, set_client_DH_params → dh_gen_ok)
• 🔄 initConnection + invokeWithLayer wrapper
• 🔄 RPC methods (sendMessage, getDialogs, getMe)

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Requirements

• C++17 compiler (MSVC, GCC, Clang)
• OpenSSL (libcrypto)
• Windows (Linux/macOS port planned — transport layer uses WinSock)

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Comparison with alternatives

Library	Language	Stealth	Dependencies	Lines
desktop-mtproto	C++ + Python	MAX	OpenSSL only	~400
TDLib (via pytdbot)	C++ + Python	MED (10 detectable signals)	Zlib, OpenSSL	100k+
Telethon	Pure Python	LOW (lang_pack='')	Pycryptodome	~50k
Pyrogram	Python C	LOW (lang_pack='')	Pycryptodome	~30k
opentele2	Pure Python	MED (lang_pack='tdesktop' but Telethon under hood)	Telethon	~55k