HervE wrote:Isn't OTRS supposed to encrypt a PGP file for a customer using its public key, or decrypt a PGP file that a customer sent using our public key (gpg being behind all that like a black box)?
What's the use of an integrated PGP interface in OTRS otherwise?
OTRS doesn't do anything to match a user to a key. At least, not explicitly.
I'm sure I'll get something wrong here, but off the top of my head is the following:
When a mail client decides it wishes to encrypt an email, it encrypts with the recipient's public key. The mail client doesn't know anything about how to do it. It just knows who the recipient is. The PGP/GPG client says, "I can handle that! What's the email address?" and then it looks up the email address in the file system stored keyring (completely separate from the application that is asking for encryption) and says, "Hey, I have that email address! I know how to encrypt a message for that recipient! Here's the encrypted version of the text you sent to pgp/gpg! Replace the body and send!" The plugin for the mail sender replaces the body with the encrypted text and sends it to the recipient.
When a customer sends an encrypted email to you (including OTRS), the customer must have your public encryption key. (This is equivalent to you providing open locks for people to put on a gym locker. They'll put something in a gym locker, grab a lock from the table, lock the locker, and hope you have the key. But you wouldn't provide a public lock if you didn't have the key.)
What OTRS does is sense that the message is encrypted, "Hey, pgp/gpg, I don't know what to do with this. This is the password for my private key. Tell me what the clear text is." And pgp unlocks/decrypts the message into clear and OTRS replaces the encrypted text with PGP's result, if successful.