diff --git a/swarmlab-app/src/run/app.js b/swarmlab-app/src/run/app.js
index 3c2538d..15c782b 100755
--- a/swarmlab-app/src/run/app.js
+++ b/swarmlab-app/src/run/app.js
@@ -430,13 +430,13 @@ cors(corsOptions),  (req, res, next) => {
 //function getSHA256ofJSON(input){
 //  return   require("crypto").createHash("sha256").update(JSON.stringify(input)).digest("hex");
 //}
-const getSHA256ofJSON = (data: string, inputEncoding, encoding) => {
+function getSHA256ofJSON(data, inputEncoding, encoding){
   if (!data) {
     return '';
   }
   inputEncoding = inputEncoding || 'utf-8';
   encoding = encoding || 'hex';
-  const hash = crypto.createHash('md5');
+  const hash = require("crypto").createHash('md5');
   return hash.update(JSON.stringify(data), inputEncoding).digest(encoding);
 }