code: function validateChecksum(requester, params) {
          params = params || {
              filePath: installerPath,
              expectedChecksum: _updateParams.checksum
          };
  
          var hash = crypto.createHash('sha256'),
              currentRequester = requester || "";
  
          if (fs.existsSync(params.filePath)) {
              var stream = fs.createReadStream(params.filePath);
  
              stream.on('data', function (data) {
                  hash.update(data);
              });
  
              stream.on('end', function () {
                  var calculatedChecksum = hash.digest('hex'),
                      isValidChecksum = (params.expectedChecksum === calculatedChecksum),
                      status;
  
                  if (isValidChecksum) {
                      if (process.platform === "darwin") {
                          status = {
                              valid: true,
                              installerPath: installerPath,
                              logFilePath: logFilePath,
                              installStatusFilePath: installStatusFilePath
                          };
                      } else if (process.platform === "win32") {
                          status = {
                              valid: true,
                              installerPath: quoteAndConvert(installerPath, true),
                              logFilePath: quoteAndConvert(logFilePath, true),
                              installStatusFilePath: installStatusFilePath
                          };
                      }
                  } else {
                      status = {
                          valid: false,
                          err: nodeErrorMessages.CHECKSUM_DID_NOT_MATCH
                      };
                  }
                  postMessageToBrackets(MessageIds.NOTIFY_VALIDATION_STATUS, currentRequester, status);
              });
          } else {
              var status = {
                  valid: false,
                  err: nodeErrorMessages.INSTALLER_NOT_FOUND
              };
              postMessageToBrackets(MessageIds.NOTIFY_VALIDATION_STATUS, currentRequester, status);
          }
      }
docs: Validates the checksum of a file against a given checksum
  @param {object} params - json containing {
  filePath - path to the file,
  expectedChecksum - the checksum to validate against }