diff --git a/test.py b/test.py
old mode 100644
new mode 100755
index e96debd..841a8af
--- a/test.py
+++ b/test.py
@@ -1,3 +1,6 @@
+#!/usr/bin/env python2
+# # -*- coding: utf-8 -*-
+
 import sys
 import os
 import unittest
diff --git a/test_backup_restore.py b/test_backup_restore.py
index b47fe9f..7be520f 100755
--- a/test_backup_restore.py
+++ b/test_backup_restore.py
@@ -38,8 +38,8 @@ parser.add_argument('-v', '--verbose', action="store_true",
                     help='Print debug information')
 parser.add_argument('-r', '--restore', action="store_true",
                     help='Restore from backup')
-parser.add_argument('-F', '--filename',
-                    help='backup filename', default='')
+parser.add_argument('filename', nargs='?',
+                    help='backup filename (default [serialnumber].bak)', default='')
 
 args = parser.parse_args()
 
@@ -64,6 +64,8 @@ try:
         users = conn.get_users()
         final = time.time()
         print ('Read {} users took {:.3f}[s]'.format(len(users), final - inicio))
+        if len(users) == 0:
+            raise BasicException("Empty user list, aborting...")
         print ("Read Templates...")
         inicio = time.time()
         templates = conn.get_templates()
@@ -92,13 +94,28 @@ try:
             raise BasicException("file with different version... aborting!")
         if data['fp_version'] != fp_version:
             raise BasicException("fingerprint version mismmatch {} != {} ... aborting!".format(fp_version, data['fp_version']))
+        #TODO: check data consistency...
+        print ("INFO: ready to write {} users".format(len(data['users'])))
+        print ("INFO: ready to write {} templates".format(len(data['templates'])))
+        #input serial number to corroborate.
         print ('WARNING! the next step will erase the current device content.')
         print ('Please input the serialnumber of this device [{}] to acknowledge the ERASING!'.format(serialnumber))
         new_serial = input ('Serial Number    : ')
         if new_serial != serialnumber:
             raise BasicException('Serial number mismatch')
-        print ('Erasing device!!! Work in progress')
-        print ('Restoring Data... Work in progress')
+        conn.disable_device()
+        print ('Erasing device...')
+        conn.clear_data()
+        print ('Restoring Data...')
+        for u in data['users']:
+            #look for Templates
+            temps = list(filter(lambda f: f.uid ==u.uid, data['templates']))
+            #print ("user {} has {} fingers".format(u.uid, len(temps)))
+            conn.save_user_template(u,temps)
+        conn.enable_device()
+        print ('--- final sizes & capacity ---')
+        conn.read_sizes()
+        print (conn)
 except BasicException as e:
     print (e)
     print ('')
diff --git a/zk/base.py b/zk/base.py
index aa387da..c0f8b04 100644
--- a/zk/base.py
+++ b/zk/base.py
@@ -109,6 +109,7 @@ class ZK(object):
         self.ommit_ping = ommit_ping
         self.verbose = verbose
         self.encoding = encoding
+        User.encoding = encoding
         self.tcp = False
         self.users = 0
         self.fingers = 0
@@ -775,14 +776,18 @@ class ZK(object):
             return False #some devices doesn't support sound
             #raise ZKErrorResponse("can't test voice")
 
-    def set_user(self, uid, name, privilege=0, password='', group_id='', user_id='', card=0):
+    def set_user(self, uid=None, name='', privilege=0, password='', group_id='', user_id='', card=0):
         '''
         create or update user by uid
         '''
         command = const.CMD_USER_WRQ
+        if uid is None:
+            uid = self.next_uid # keeps uid=0
+            if not user_id:
+                user_id = self.next_user_id # else...
         if not user_id:
             user_id = str(uid) #ZK6 needs uid2 == uid
-        #uid = chr(uid % 256) + chr(uid >> 8)
+        #TODO: check what happens if name is missing...
         if privilege not in [const.USER_DEFAULT, const.USER_ADMIN]:
             privilege = const.USER_DEFAULT
         privilege = int(privilege)
@@ -827,8 +832,8 @@ class ZK(object):
                     raise ZKErrorResponse("Can't find user")
         if isinstance(fingers, Finger):
             fingers = [fingers]
-        fpack = ""
-        table = ""
+        fpack = b""
+        table = b""
         fnum = 0x10 # possibly flag
         tstart = 0
         for finger in fingers:
diff --git a/zk/user.py b/zk/user.py
index 265953f..7a5fbe6 100644
--- a/zk/user.py
+++ b/zk/user.py
@@ -1,21 +1,25 @@
 # -*- coding: utf-8 -*-
 from struct import pack #, unpack
 class User(object):
+    encoding = 'UTF-8'
 
     def __init__(self, uid, name, privilege, password='', group_id='', user_id='', card=0):
         self.uid = uid
         self.name = str(name)
         self.privilege = privilege
         self.password = str(password)
-        self.group_id = group_id
+        self.group_id = str(group_id)
         self.user_id = user_id
         self.card = card # 64 int to 40 bit int
+
     def repack29(self): # with 02 for zk6 (size 29)
-        return pack("<BHB5s8sIxBhI", 2, self.uid, self.privilege, self.password, self.name, self.card, int(self.group_id) if self.group_id else 0, 0, int(self.user_id))
+        return pack("<BHB5s8sIxBhI", 2, self.uid, self.privilege, self.password.encode(User.encoding, errors='ignore'), self.name.encode(User.encoding, errors='ignore'), self.card, int(self.group_id) if self.group_id else 0, 0, int(self.user_id))
+
     def repack73(self): #with 02 for zk8 (size73)
         #password 6s + 0x00 + 0x77
         # 0,0 => 7sx group id, timezone?
-        return pack("<BHB8s24sIB7sx24s", 2, self.uid, self.privilege,self.password, self.name, self.card, 1, self.group_id, str(self.user_id))
+        return pack("<BHB8s24sIB7sx24s", 2, self.uid, self.privilege,self.password.encode(User.encoding, errors='ignore'), self.name.encode(User.encoding, errors='ignore'), self.card, 1, str(self.group_id).encode(User.encoding, errors='ignore'), str(self.user_id).encode(User.encoding, errors='ignore'))
+
     def __str__(self):
         return '<User>: [uid:{}, name:{} user_id:{}]'.format(self.uid, self.name, self.user_id)