Extract TOTP/HOTP secret keys from Google Authenticator

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

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
   

Requirement

The protobuf package of Google for proto3 is required for running this script. protobuf >= 3.14 is recommended.

pip install protobuf

Known to work with

• Python 3.6.12 and protobuf 3.14.0
• Python 3.8.5 and protobuf 3.14.0

Optional

For printing QR codes, the qrcode module is required

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):

protoc --python_out=generated_python google_auth.proto

References

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