In bitcoin (and other crypto currencies) usually a mnemonic phrase (also commonly called seed) [*] (commonly 12-24 human memorable words) are created as a backup which can deterministically create all wallet sub public and private keys. So one only has to remember these words and would always be able to restore its keys.
(These seed even allow creation of keys for different crypto currencies. In future, perhaps even for OpenPGP keys.)
- That makes a file based backup optional if the phrase is memorized.
- Allows easy paper backups with a pen.
Draft of mnemonic phrase for OpenPGP / GnuPG / gpg keys:
- https://github.com/taelfrinn/bip44extension and look for Deterministic GPG keys
([*] The crypto currency communities use the term seed differently than the GnuPG community.)
- please implement mnemonic phrase based backups (key creation) for OpenPGP keys
- please get in touch with the authors of https://github.com/taelfrinn/bip44extension