(PECL gnupg >= 0.1)
gnupg_sign — Signs a given text
Signs the given plaintext with the keys, which were
set with gnupg_addsignkey before and
returns the signed text or the signature, depending on what was set with
gnupg_setsignmode.
identifierThe gnupg identifier, from a call to gnupg_init() or gnupg.
plaintextThe plain text being signed.
On success, this function returns the signed text or the signature.
On failure, this function returns false.
Example #1 Procedural gnupg_sign() example
<?php
$res = gnupg_init();
gnupg_addsignkey($res,"8660281B6051D071D94B5B230549F9DC851566DC","test");
$signed = gnupg_sign($res, "just a test");
echo $signed;
?>Example #2 OO gnupg_sign() example
<?php
$gpg = new gnupg();
$gpg->addsignkey("8660281B6051D071D94B5B230549F9DC851566DC","test");
$signed = $gpg->sign("just a test");
echo $signed;
?>It's a bit confusing how the "keyinfo" for a key returns "can_sign".
If you have only added your Public Key, it will indicate "can_sign" for the key in "keyinfo", but that doesn't mean yet, that you can sign with the key. You will also need to add your Private Key to actually make signing work.