Gpg encrypt with public key

Question

The php.net website contains information on how to encrypt the information with its own key.

$gpg = new gnupg();
$gpg -> addencryptkey("8660281B6051D071D94B5B230549F9DC851566DC");
$enc = $gpg -> encrypt("just a test");
echo $enc;

But if I wanted to encrypt a message having only the public key of the recipient of the message?

How is this possible?

Answer 1

Looks like you should first add the public key to GnuPG keyrings, and after that call addencryptkey() with that key's fingerprint.