diff --git a/google_keep_tasks/auth.py b/google_keep_tasks/auth.py
index 238c2cd..518c672 100644
--- a/google_keep_tasks/auth.py
+++ b/google_keep_tasks/auth.py
@@ -21,8 +21,12 @@ class GoogleKeepFileAuth(object):
     def __init__(self, file=None):
         self.file = file or AUTH_FILE
 
-    def save_credentials(self, username, password):
-        data = {'username': username, 'password': password}
+    def save_credentials(self, username, password=None, master_token=None):
+        data = {'username': username}
+        if master_token:
+            data['master_token'] = master_token
+        elif password:
+            data['password'] = password
         directory = os.path.dirname(AUTH_FILE)
         if not os.path.exists(directory):
             os.makedirs(directory, 0o700)
@@ -37,9 +41,18 @@ def get_credentials(self):
             raise LoginError('Invalid json from credentials file: {}. Error: {}'.format(
                 self.file, e
             ))
-        if not isinstance(data, dict) or 'username' not in data or 'password' not in data:
-            raise LoginError('Invalid credentials format file. username and password are required.')
-        return data['username'], data['password']
+        if not isinstance(data, dict) or 'username' not in data:
+            raise LoginError('Invalid credentials format file. username is required.')
+        
+        # Support both old (password) and new (master_token) format
+        username = data['username']
+        master_token = data.get('master_token')
+        password = data.get('password')
+        
+        if not master_token and not password:
+            raise LoginError('Either password or master_token is required.')
+        
+        return username, password, master_token
 
 
 class GoogleKeep(object):
@@ -50,9 +63,9 @@ def __init__(self):
     def login_or_input(self):
         auth_changed = False
         input_login = False
-        username = password = None
+        username = password = master_token = None
         try:
-            username, password = self.auth.get_credentials()
+            username, password, master_token = self.auth.get_credentials()
         except UnavailableLoginError:
             click.echo('Welcome to Google Keep. Enter your username and password below. '
                        'If your account is protected, you need an application password: '
@@ -66,8 +79,12 @@ def login_or_input(self):
                 # Request new credentials
                 auth_changed = True
                 username, password = self.get_credencials_assistant(username)
+                master_token = None
             try:
-                self.keep.login(username, password)
+                if master_token:
+                    self.keep.resume(username, master_token)
+                else:
+                    self.keep.login(username, password)
             except LoginException:
                 choice = choices_prompt('Authentication failed, what do you want to do?', [
                     'Enter new credentials',
@@ -82,7 +99,7 @@ def login_or_input(self):
                     raise Abort
             else:
                 if auth_changed:
-                    self.auth.save_credentials(username, password)
+                    self.auth.save_credentials(username, password, master_token)
                 break
 
     def get_credencials_assistant(self, default_username):