Renew public key

• Save public key to external storage
• Boot Tails in offline mode
• Make private key available for use
• Renew subkeys:
  • gpg --edit-key <key>
  • key 1, key 2, etc.
  • expire
  • save
• Export new public key: gpg --export --armor > key.asc
• Save public key to external storage
• Boot back to normal OS
• Copy new public key to disk and import: gpg --import key.asc
• Send keys to key servers: gpg --send-keys <key>