code: private final boolean checkHeader(int signature)
      {
          // check the signature
          // Trie in big-endian US-ASCII (0x54726965).
          // Magic number to authenticate the data.
          if (signature != HEADER_SIGNATURE_) {
              return false;
          }
  
          if ((m_options_ & HEADER_OPTIONS_SHIFT_MASK_) !=
                                                      INDEX_STAGE_1_SHIFT_ ||
              ((m_options_ >> HEADER_OPTIONS_INDEX_SHIFT_) &
                                                  HEADER_OPTIONS_SHIFT_MASK_)
                                                   != INDEX_STAGE_2_SHIFT_) {
              return false;
          }
          return true;
      }
docs: Authenticates raw data header.
  Checking the header information, signature and options.
  @param signature This contains the options and type of a Trie
  @return true if the header is authenticated valid