code: public void initSwfVerification(String swfFilePath) {
          log.info("Initializing swf verification for: {}", swfFilePath);
          byte[] bytes = null;
          if (swfFilePath != null) {
              File localSwfFile = new File(swfFilePath);
              if (localSwfFile.exists() && localSwfFile.canRead()) {
                  log.info("Swf file path: {}", localSwfFile.getAbsolutePath());
                  bytes = FileUtil.readAsByteArray(localSwfFile);
              } else {
                  bytes = "Red5 is awesome for handling non-accessable swf file".getBytes();
              }
          } else {
              bytes = new byte[42];
          }
          calculateHMAC_SHA256(bytes, 0, bytes.length, GENUINE_FP_KEY, 30, swfHash, 0);
          swfSize = bytes.length;
          log.info("Verification - size: {}, hash: {}", swfSize, Hex.encodeHexString(swfHash));
      }
docs: Initialize SWF verification data.
  
  @param swfFilePath path to the swf file or null