Useful function for getting a random key
private function _getRandomKey($md5=false){
$char = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
$key = '';
$char_length = strlen($char)-1;
for ($i = 0; $i != 32; $i++){
$random_pos = rand(0, $char_length);
$key .= $char{$random_pos};
}
return $key = $md5 ? md5($key) : $key;
}