Added var to properly declare local variables so that they don't pollute the global namespace and risk multi-threading conflicts.
diff --git a/js/securityLib/rsasign-1.2.js b/js/securityLib/rsasign-1.2.js
index 1f02f80..0da2827 100644
--- a/js/securityLib/rsasign-1.2.js
+++ b/js/securityLib/rsasign-1.2.js
@@ -313,9 +313,9 @@
 	  	msgHashValue = ff(byteArray);

 	  } else {

 	  	// Compute merkle hash

-		  h = hex_sha256_from_bytes(byteArray);

-		  index = witness.path.index;

-		  for (i = witness.path.digestList.length - 1; i >= 0; i--) {

+		  var h = hex_sha256_from_bytes(byteArray);

+		  var index = witness.path.index;

+		  for (var i = witness.path.digestList.length - 1; i >= 0; i--) {

 		  	var str = "";

 		  	if (index % 2 == 0) {

 		  		str = h + witness.path.digestList[i];