Generador de Valores Hexadecimales - PHP

function RandomString($length=10,$uc=TRUE,$n=TRUE,$sc=FALSE)
    {
        $source = 'abcdef';
        if($uc==1) $source .= 'ABCDEF';
        if($n==1) $source .= '1234567890';
        if($sc==1) $source .= '|@#~$%()=^*+[]{}-_';
        if($length>0)
        {
            $rstr = "";
            $source = str_split($source,1);
            for($i=1; $i<=$length; $i++)
            {
                mt_srand((double)microtime() * 1000000);
                $num = mt_rand(1,count($source));
                $rstr .= $source[$num-1];
            }

        }
        return $rstr;
    }