Questions about finding keys used to encrypt files with gpg

[mattia.codato]

Hi, i've encrypted some files from my hd using the gpg -c [filename] command.

As usual gpg prompted me for a passhprase and then created the encrypted files, so far it worked out perfectly.

I noticed that the gpg -d [filename] command works out without asking me for the passphrase, so after a brief search i became aware of the fact that gpg uses public/private keys encrypting, combined with a passphrase.

Having i used the gpg -c command straight out of the box (so no explicit key setup was made before running the command), i suppose the gpg command used some kind of default keys or something like that.

Unfortunately running the gpg --list-keys or gpg --list-secret-keys command gives nothing in output, so i guess no keys is really installed.

As far as i know, in order to succesfully export and decrypt the files in other computers, one must export and restore the original key pairs used to encrypt the original files. So what should i do to figure it out what kind of keys were used ?

Regards

Mattia