QR Codes for Storing Private Keys

So, storage of private keys is a problem.

Just storing it on your computer isn't such a big problem - hopefully, you're storing it encrypted using software whose encryption you trust.

However, backing them up - that's another issue. Do you trust storing them in the cloud? I don't. Do you keep them on a backup disk or USB dongle? What if they fail?

After looking over the options, I found this post at the ever-excellent StackExchange. Basically, the idea is that you convert the ASCII exported private key to a QR code, print that, note the key ID on the printed copy, and then delete (securely) the exported private key. You then keep the printed QR code somewhere safe - a safe in your house or in a safe deposit box. Then, you can use a QR scanner to convert it back to ASCII (it's still secure because you'll need your passphrase to use the key).

In the post, they recommend using an online QR scanner that uses javascript so it all happens in the browser. Since I'm much more paranoid than that, I just use qrencode on my MacBook, like so:

Install qrencode:

$ brew install qrencode

Export the secret key and covert it to a QR code:

$ gpg --export-secret-key -a | qrencode -l L -8 -o key.png

Then you just print the QR code and then securely delete it.