Downgrade GnuPG Keys

Keys created with newer GnuPG versions cannot be read with older versions. We need to export and import them properly.

1. Make a backup of the .gnupg directory of the new GnuPG version:

         cp -pR .gnupg .gnupg-backup
       

2. Change the integrity protection of the key to a simpler checksum known by older versions of GnuPG:

         gpg --simple-sk-checksum --edit-key <key>
         ...
         Command> passwd
         ...
         Enter passphrase:
         ...
         Enter the new passphrase for this secret key.
         Enter passphrase:
         Repeat passphrase: 
         ...
         Command> save
       

3. Export the secret and public keys:

         gpg --export-secret-key <key> > key.sec
         gpg --export <key> > key.pub
       

4. Import the keys with the older GnuPG version:

         gpg --allow-secret-key-import --import key.sec
         gpg --import key.pub
       

5. When you are done with all keys you wanted to downgrade, restore the backup from step 1.

Oliver Hitz, 20030703

Disclaimer: This information is provided "as is", with absolutely no warranty expressed or implied. Any use is at your own risk.