Return None if the data can not be dencrypted

module.py

@@ -1006,7 +1006,10 @@ def serve_qrcode():
 #    Data decryption
 
 def do_decrypt( data ):
-    return AESCipher( session[ 'password' ] ).decrypt( data )
+    try:
+        return AESCipher( session[ 'password' ] ).decrypt( data )
+    except:
+        return None
 
 def do_encrypt( data ):
     return AESCipher( session[ 'password' ] ).encrypt( data )