You CAN list all keys in the keyring, you only have to pass an empty string ''.
<?php
$gpg = new gnupg();
$info = $gpg -> keyinfo('');
print_r($info);
?>
That's it! ;)(PECL gnupg >= 0.1)
gnupg_keyinfo — Returns an array with information about all keys that matches the given pattern
identifierGnupg tanıtıcısı, bir gnupg_init() çağrısından veya gnupg nesnesinden elde edilir.
patternThe pattern being checked against the keys.
   Returns an array with information about all keys that matches the given
   pattern or false, if an error has occurred.
  
Örnek 1 Procedural gnupg_keyinfo() example
<?php
$res = gnupg_init();
$info = gnupg_keyinfo($res, 'test');
print_r($info);
?>Örnek 2 OO gnupg_keyinfo() example
<?php
$gpg = new gnupg();
$info = $gpg->keyinfo("test");
print_r($info);
?>You CAN list all keys in the keyring, you only have to pass an empty string ''.
<?php
$gpg = new gnupg();
$info = $gpg -> keyinfo('');
print_r($info);
?>
That's it! ;)Returns an array of information blocks. An information block looks like
<?php
array (
    'disabled' => <bool>,
    'expired' => <bool>,
    'revoked' => <bool>,
    'is_secret' => <bool>,
    'can_sign' => <bool>,
    'can_encrypt' => <bool>,
    'uids' => <array of uid blocks>,
    'subkeys' => <array of subkey blocks>,
)
?>
An uid data block looks like
<?php
array (
    'name' => <string>,
    'comment' => <string>,
    'email' => <string>,
    'uid' => <string>,
    'revoked' => <bool>,
    'invalid' => <bool>,
)
?>
A subkey block looks like
<?php
array (
    'fingerprint' => <string>,
    'keyid' => <string>,
    'timestamp' => <int>,
    'expires' => <int>,
    'is_secret' => <bool>,
    'invalid' => <bool>,
    'can_encrypt' => <bool>,
    'can_sign' => <bool>,
    'disabled' => <bool>,
    'expired' => <bool>,
    'revoked' => <bool>,
),
?>