向WP登陆页加验证框

<?

function bd_login_form()
{
?>
	<p>
		<label for="user_pass_2">身份确认码<br />
		<input type="password" name="pwd_2" id="user_pass_2" value="" size="20" tabindex="20" /></label>
	</p>
<?
}
add_action('login_form', 'bd_login_form');

function bd_authenticate_username_password($user, $username = '', $password = '')
{
	if ( isset($_POST['log']) )
	{
		$bDone = false;
		if ( isset( $_REQUEST['pwd_2'] ) )
		{
			$pwd2 = $_REQUEST['pwd_2'];
			if ( $pwd2 === '123' ) // 自由发挥
				$bDone = true;
		}
		if ( $bDone == false )
		{
			remove_filter('authenticate', 'wp_authenticate_username_password', 20, 3);
			$error = new WP_Error();
			$error->add('incorrect_password', __('<strong>错误</strong>：身份确认码不正确。'));
			return $error;
		}
	}
	return $user;
}
add_filter('authenticate', 'bd_authenticate_username_password');

?>

直接放到主题的functions.php内就用得了，或者自己整成插件。