As many of you likely know, duplicity is a software program primarily used on Linux operating systems for creating backups of your desktop environment. The software is known to use gpg to encrypt the backup files for privacy reasons.
Now my question is the following: how do you both encrypt and digitally sign your backup files? When used without any command parameters, the software simply prompts the user for a passphrase and then it symmetrically encrypts the files by default using it.
But how do you also digitally sign in the process. The manual talks about the --sign-key and --encrypt-key parameters that need to be passed but trying different combinations, I could never figure out how to do it.
UPDATE: as pointed out in the comment section, I was using the encrypt command wrong. Apparently you need to use the same keyID from GPG for both --sign-key or --encrypt-key (and thus the same passphrase for both). A revised question now would be: how is passing a public-private keypair to GPG for symmetric encryption via the keyID work (does it encrypt using the private key? And if so, is it the standard symmetric algorithm used for encryption?). Also, is it possible to symmetrically encrypt with one keyID and sign with a different key from gpg?