56    public static function parseMessage(
string $message, 
int &$counter) : ?string{
 
   57        $delimiterPos = strrpos($message, self::TOKEN_DELIMITER);
 
   58        if($delimiterPos !== 
false){
 
   59            $left = substr($message, 0, $delimiterPos);
 
   60            $right = substr($message, $delimiterPos + strlen(self::TOKEN_DELIMITER));
 
   61            $expectedToken = hash(self::TOKEN_HASH_ALGO, $left, options: [
'seed' => $counter]);
 
   63            if($expectedToken === $right){