Yejun Su

Sep 18, 2023

Backup GnuPG private key

gpg-toolkit is inspired by this article.

I’m using GNU Privacy Guard (GnuPG or GPG) in several places: encrypting passwords, signing git commits, decrypting emails, etc. So it’s time to find a way to backup the GPG private key.

I asked GPT-4 for a method to keep the private key safe, and it tells me to convert it to QR code and print it on the paper. That’s a good idea! I’ll start from backup to a printable text, and then the QR code.


Before backup, you need to know your GPG key ID. Run this command:

gpg --list-keys --keyid-format long

It will list all the public keys in your system. Search your own key according to this format pub rsa2048/{YOUR KEY ID}, the {YOUR KEY ID} part is your GPG key ID.

Then export both the public and private key:

gpg --export-secret-keys {YOUR KEY ID} > private-key.gpg
gpg --export {YOUR KEY ID} > public-key.gpg

Backup to printable text

One of the program to be used is paperkey, it transforms the GPG private key to a printable format. The usage is straightforward:

# backup
paperkey --secret-key private-key.gpg --output printable.txt

Keep in mind that you need both the public key and the printable text to restore the private key:

# restore
paperkey --pubring public-key.gpg --secrets printable.txt --output restored-private-key.gpg

Backup to QR code

The process is similar to the previous method, but it requires two more programs: qrencode to create QR code and zbar to read QR code. Generally speaking, the more programs you rely on, the more friction you run into. But I just tried it for fun:

# backup
paperkey --output-type raw --secret-key private-key.gpg | base64 | qrencode -o qrcode.png

With the public key and QR code in hand, you can restore the private key:

# restore
zbarimg qrcode.png | cut -d':' -f2 | base64 --decode | paperkey --pubring public-key.gpg --output restored-private-key.gpg