tdata-extract

Extract the Auth Key (hex) and DC ID from a Telegram Desktop tdata folder — fully local, offline, passcode-aware. No network, no login, no API credentials. Built for the forensics / account-migration niche where you need to attach an MTProto library to an existing Desktop session.

Works on current Telegram Desktop (v6.x, tested on 6.9). No opentele dependency — a self-contained parser, so it keeps working when a new release bumps the tdata format.

Install

pip install -r requirements.txt   # just `cryptography`

Python 3.8+.

Usage

python tdata_extract.py <path/to/tdata> [--passcode PASS] [--json] [--out FILE]

Flag	Meaning
--passcode PASS	The Desktop local passcode, if one is set. Omit it if there is none.
--json	Emit JSON instead of plain text.
--out FILE	Write to FILE instead of stdout.

Example:

$ python tdata_extract.py ~/Telegram/tdata
user_id=123456789 dc_id=2
    auth_key=a1b2c3…            # 256-byte key = 512 hex chars

JSON (--json):

[
  { "user_id": 123456789, "dc_id": 2, "auth_key": "a1b2c3…" }
]

The dc_id + auth_key pair is exactly what MTProto libraries (Telethon, Pyrogram, TDLib) need to attach to an existing session. All accounts in a multi-account tdata are extracted. A wrong or missing passcode exits with a clear message (could not unlock key_data …), not a key.

How it works

tdata stores each account's session in the encrypted MTP authorization block (dbiMtpAuthorization), whose layout has been stable since 2021 (the 64-bit user-id migration). Older extractors (opentele) break on new releases because they fully parse the account map, which keeps gaining new lskType keys each version (custom-emoji, prefs, webview tokens, …) — one unknown key aborts the whole load with "No account has been loaded."

This tool sidesteps that entirely:

1. Read key_datas → derive the local key (PBKDF2-HMAC-SHA512 over the salt + optional passcode).
2. Walk every tdata file and AES-IGE-decrypt each with the local key.
3. Locate the dbiMtpAuthorization block by signature and parse user_id, main_dc_id, and the per-DC 256-byte auth_key directly — the map is never touched.

Because it reads only the stable auth block, it is resilient to map/draft format churn across Telegram Desktop versions.

Security & ethics

• Use only on tdata for accounts you own and are authorized to access. Extracting or using session data from other people's accounts may be illegal and violates Telegram's Terms of Service.
• An auth_key is a full account credential — equivalent to being logged in, and it bypasses your 2FA/cloud password. Treat it like a private key: keep it offline, do not paste it into chats, pastebins, or issue trackers, and delete extracted copies when you are done.
• The tool itself makes no network connection and never transmits anything.

Limits (honest)

• Reads the MTP auth block only — not message history, drafts, cache, or the account map. If that is what you need, use opentele/TDLib directly.
• Tested against Telegram Desktop v6.x. Pre-2021 legacy narrow-id tdata is handled; other ancient layouts are not a target.
• Requires a readable, unlocked-on-disk tdata plus the passcode if one is set. It cannot brute-force or recover a forgotten passcode.
• A hardware-key / system-keychain–sealed tdata is out of scope.

Support

If this saved you time, a ⭐ on the repo helps — and tips are welcome:

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Disclaimer

Provided as is, without warranty of any kind. The authors accept no liability for misuse.

License

MIT — see LICENSE.