With GPG I can encrypt file symmetrically, as for example described here: How do I symmetrically encrypt a file using gpg?. On decryption it will show (among other lines):
gpg: encrypted with 1 passphrase
How can I add more than one passphrase on encrypting the file?
- I know it is possible to add multiple recipients in the asymmetric encryption.
One can encrypt the file both symmetric and asymmetric at the same time. From the manpage of
-e Encrypt data. This option may be combined with --sign (for a signed and encrypted message), --symmetric (for a message that may be decrypted via a secret key or a passphrase), [...]
A message on the gnupg mailing list from 2004 indicates that it is not yet possible. Now almost 10 years later and this might not be correct anymore.