code: public function decrypt($data)
      {
          if (!is_string($data) || !preg_match('/^[0-9A-Fa-f]*$/', $data)) {
              throw new \InvalidArgumentException('blowfishDecryptCBC require hex input', 1502);
          }
  
          $data = pack('H*', $data);
  
          if ($this->iv === null) {
              $return = mcrypt_decrypt($this->cipher, $this->key, $data, $this->mode);
          } else {
              $return = mcrypt_decrypt($this->cipher, $this->key, $data, $this->mode, $this->iv);
          }
  
          return rtrim($return, "\0");
      }
docs: Decrypt the data string
  
  @param  string $data
  @return mixed
  @throws \InvalidArgumentException