code: public byte[] sectionHash(int sectionNumber, MessageDigest messageDigest)
              throws IOException {
          SectionTable table = data.getSectionTable();
          SectionHeader header = table.getSectionHeader(sectionNumber);
          long start = header.getAlignedPointerToRaw();
          long end = new SectionLoader(data).getReadSize(header) + start;
          if (end <= start) {
              logger.warn("The physical section size must be greater than zero!");
              return new byte[0];
          }
          return computeHash(data.getFile(), messageDigest, start, end);
      }
docs: Returns the hash value of the section with the section number and the
  messageDigest.
  <p>
  The section's size must be greater than 0, otherwise the returned array
  has zero length.
  
  @param sectionNumber
  the section's number
  @param messageDigest
  the message digest algorithm
  @return hash value of the section with the section number
  @throws IOException