paperkey

An OpenPGP key archiver. More information: https://www.jabberwocky.com/software/paperkey/.

• Take a specific secret key and generate a text file with the secret data:
  paperkey --secret-key {{path/to/secret_key.gpg}} --output {{path/to/secret_data.txt}}
• Take the secret key data in secret_data.txt and combine it with the public key to reconstruct the secret key:
  paperkey --pubring {{path/to/public_key.gpg}} --secrets {{path/to/secret_data.txt}} --output {{secret_key.gpg}}
• Export a specific secret key and generate a text file with the secret data:
  gpg --export-secret-key {{key}} | paperkey --output {{path/to/secret_data.txt}}