Extract TOTP/HOTP secret keys from Google Authenticator

Extract two-factor authentication (2FA, TFA) secret keys from export QR codes of "Google Authenticator" app

Testing Status

Usage

1. Export the QR codes from "Google Authenticator" app

2. Read QR codes with QR code reader

3. Save the captured QR codes in a text file. Save each QR code on a new line. (The captured QR codes look like otpauth-migration://offline?data=...)

4. Call this script with the file as input:

    python extract_otp_secret_keys.py -p example_export.txt
   

Dependencies

pip install -r requirements.txt

Known to work with

• Python 3.10.6, protobuf 4.21.5, qrcode 7.3.1, and pillow 9.2

Optional

For printing QR codes, the qrcode module is required, otherwise it can be omitted.

pip install qrcode[pil]

Technical background

The export QR code of "Google Authenticator" contains the URL otpauth-migration://offline?data=.... The data parameter is a base64 encoded proto3 message (Google Protocol Buffers).

Command for regeneration of Python code from proto3 message definition file (only necessary in case of changes of the proto3 message definition or new protobuf versions):

protoc --python_out=protobuf_generated_python google_auth.proto

The generated protobuf Python code was generated by protoc 21.5 (https://github.com/protocolbuffers/protobuf/releases/tag/v21.5).

References

• Proto3 documentation: https://developers.google.com/protocol-buffers/docs/pythontutorial
• Template code: https://github.com/beemdevelopment/Aegis/pull/406

Alternative installation methods

venv

Alternatively, you can use a python virtual env for the dependencies:

python -m venv venv
. venv/bin/activate
pip install -r requirements-buildenv.txt
pip install -r requirements.txt

The requirements*.txt files contain all the dependencies (also the optional ones). To leave the python virtual env just call deactivate.

devbox

Install devbox, which is a wrapper for nix. Then enter the environment with Python and the packages installed with:

devbox shell

Tests

unittest

There are basic unit tests, see unittest_extract_otp_secret_keys.py.

Run unit tests:

python -m unittest

PyTest

There are basic pytests, see test_extract_otp_secret_keys.py.

Run pytests:

pytest unittest

or

python -m pytest