The purpose of this project is to establish a more secure alternative to paper backups while keeping the content of backups as interoperable* as possible.

*Using GnuPG is not the most secure option given SHA512 is (more) vulnerable to brute-force attacks (using Argon2, for example, would be more secure, but would require using code to access backups vs simply piping the output of the QR code to gpg making backups less interoperable).

This above thought process is open for debate.

git clone https://github.com/sunknudsen/qr-backup.git
cd qr-backup
pipenv install

The following example can be used to create an encrypted paper backup of a Bitcoin BIP39 12-word mnemonic.

$ echo "essence wisdom demise insane vital kitchen pet swarm robust warfare innocent dolphin" | gpg --s2k-mode 3 --s2k-count 65011712 --s2k-digest-algo sha512 --cipher-algo AES256 --symmetric --armor | pipenv run python main.py
-----BEGIN PGP MESSAGE-----

jA0ECQMKNs6jBO8yqrH/0oQBlJhnD0tdAR0dhXujIO1m0PfiC+E37PjMG9MMUkkE
hz+jKFKz/3PtzsfSFOJP/G5fvVWhw+zBniD/ScW7EQbTnv6rmSsf/AU67u8bYqZ5
EywNfq2Cn0f7pqvJ44wUEDebxP9JaJ5yprXZkSUzZOwkD1RGNK9tJ6bJNIRQactL
LnSvne0=
=wIB/
-----END PGP MESSAGE-----

Displayed QR code

• Secure by design (dependability)
• Runs on Python (increased interoperability)
• Runs on Raspberry Pi (affordability, cold* computing, compartmentalization and Intel SE mitigation)
• As few dependencies as possible (increased interoperability and easy code audits)
• Framebuffer support on Raspberry Pi OS (32-bit) Lite (does not require desktop environment)
• Memory implementation (does not require filesystem)

*Once configured, Bluetooth and Wi-Fi are disabled.

echo "dtoverlay=disable-bt" | sudo tee -a /boot/config.txt
echo "dtoverlay=disable-wifi" | sudo tee -a /boot/config.txt
sudo reboot

• Figure out how to display QR code using framebuffer without writing file to filesystem (leading to removal of opencv-python dependency which currently doesn’t work on Raspberry Pi OS (32-bit) Lite without multiple additional apt installs)
• Figure out how to display QR code using framebuffer on desktop environments such as macOS

Thanks so much for contributing to this project. 🤓

Please sign pull requests.