You do. That comment of mine, as is, is entirely worthless.

The sender (in this case, that would be me) needs to encrypt the message using either:

1. The public key of the recipient
2. A custom passphrase
3. Any combination of the above, including multiple different public keys

That way, the only people who can decrypt the message is a person with the private key that is paired with any of the public keys that the message was encrypted with OR literally anybody that happens to have the passphrase it was encrypted with.

I think I had encrypted that message using just my own public key, so as I said, the message is completely useless to anybody but myself.