diff --git a/dash_auth/oauth.py b/dash_auth/oauth.py
index b980bbd..2e102f9 100644
--- a/dash_auth/oauth.py
+++ b/dash_auth/oauth.py
@@ -1,9 +1,9 @@
 from __future__ import absolute_import
-import datetime
 import flask
-from flask_seasurf import SeaSurf
 import json
 import os
+from textwrap import dedent
+import itsdangerous
 
 from .auth import Auth
 
@@ -14,7 +14,13 @@ class OAuthBase(Auth):
     # Name of the cookie containing the OAuth2 access token
     TOKEN_COOKIE_NAME = 'oauth_token'
 
-    def __init__(self, app, app_url, client_id=None):
+    def __init__(
+            self,
+            app,
+            app_url,
+            client_id=None,
+            secret_key=None,
+            salt=None):
         Auth.__init__(self, app)
 
         self.config = {
@@ -24,7 +30,31 @@ def __init__(self, app, app_url, client_id=None):
         self._app = app
         self._app_url = app_url
         self._oauth_client_id = client_id
-        self._access_codes = self.create_access_codes()
+
+        if secret_key is None and app.server.secret_key is None:
+            raise Exception(dedent('''
+                app.server.secret_key is missing.
+                Generate a secret key in your Python session
+                with the following commands:
+
+                >>> import os
+                >>> import base64
+                >>> base64.b64encode(os.urandom(30)).decode('utf-8')
+
+                and assign it to the property app.server.secret_key
+                (where app is your dash app instance).
+                Note that you should not do this dynamically:
+                you should create a key and then assign the value of
+                that key in your code.
+            '''))
+
+        if salt is None:
+            raise Exception(dedent('''
+                salt is missing. The salt parameter needs to a string that
+                is unique to this individual Dash app.
+            '''))
+
+        self._signer = itsdangerous.TimestampSigner(secret_key, salt=salt)
 
         app.server.add_url_rule(
             '{}_dash-login'.format(app.config['routes_pathname_prefix']),
@@ -52,36 +82,33 @@ def __init__(self, app, app_url, client_id=None):
         with open(os.path.join(_current_path, 'login.js'), 'r') as f:
             self.login_bundle = f.read()
 
-    def create_access_codes(self):
-        token = SeaSurf()._generate_token()
-        new_access_codes = {
-            'access_granted': token,
-            'expiration': (
-                datetime.datetime.now() + datetime.timedelta(
-                    seconds=self.config['permissions_cache_expiry']
-                )
+    def access_token_is_valid(self):
+        if self.AUTH_COOKIE_NAME not in flask.request.cookies:
+            return False
+
+        access_token = flask.request.cookies[self.AUTH_COOKIE_NAME]
+
+        try:
+            self._signer.unsign(
+                access_token,
+                max_age=self.config['permissions_cache_expiry']
             )
-        }
-        self._access_codes = new_access_codes
-        return self._access_codes
+            return True
+        except itsdangerous.SignatureExpired:
+            # Check access in case the user is valid but the token has expired
+            return False
+        except itsdangerous.BadSignature:
+            # Access tokens in previous versions of `dash-auth`
+            # weren't generated with itsdangerous
+            # and will raise `BadSignature`
+            return False
 
     def is_authorized(self):
         if self.TOKEN_COOKIE_NAME not in flask.request.cookies:
             return False
 
         oauth_token = flask.request.cookies[self.TOKEN_COOKIE_NAME]
-
-        if (datetime.datetime.now() > self._access_codes['expiration']):
-            self.create_access_codes()
-
-        if self.AUTH_COOKIE_NAME not in flask.request.cookies:
-            return self.check_view_access(oauth_token)
-
-        access_cookie = flask.request.cookies[self.AUTH_COOKIE_NAME]
-
-        # If there access was previously declined,
-        # check access again in case it has changed
-        if access_cookie != self._access_codes['access_granted']:
+        if not self.access_token_is_valid():
             return self.check_view_access(oauth_token)
 
         return True
@@ -118,12 +145,16 @@ def wrap(*args, **kwargs):
                 # Python 3
                 if isinstance(response, str):
                     response = flask.Response(response)
-            self.set_cookie(
-                response,
-                name=self.AUTH_COOKIE_NAME,
-                value=self._access_codes['access_granted'],
-                max_age=(60 * 60 * 24 * 7),  # 1 week
-            )
+
+            # grant a new access token if expired, missing, or invalid
+            if not self.access_token_is_valid():
+                access_token = self._signer.sign('access')
+                self.set_cookie(
+                    response,
+                    name=self.AUTH_COOKIE_NAME,
+                    value=access_token,
+                    max_age=(60 * 60 * 24 * 7),  # 1 week
+                )
             return response
         return wrap
 
diff --git a/dash_auth/plotly_auth.py b/dash_auth/plotly_auth.py
index 0be7627..80a4073 100644
--- a/dash_auth/plotly_auth.py
+++ b/dash_auth/plotly_auth.py
@@ -29,7 +29,12 @@ def __init__(self, app, app_name, sharing, app_url):
         Returns:
             None
         """
-        super(PlotlyAuth, self).__init__(app, app_url)
+        super(PlotlyAuth, self).__init__(
+            app,
+            app_url,
+            secret_key=api_requests.credential('plotly_api_key'),
+            salt=app_name
+        )
 
         self._fid = create_or_overwrite_dash_app(
             app_name, sharing, app_url
diff --git a/setup.py b/setup.py
index 24509b1..5a4f676 100644
--- a/setup.py
+++ b/setup.py
@@ -18,7 +18,8 @@
         'flask-seasurf',
         'plotly',
         'dash>=0.18.3',
-        'retrying'
+        'retrying',
+        'itsdangerous'
     ],
     include_package_data=True,
     url='https://plot.ly/dash',
diff --git a/usage_plotly_auth.py b/usage_plotly_auth.py
index 1791080..0c72ad8 100644
--- a/usage_plotly_auth.py
+++ b/usage_plotly_auth.py
@@ -18,6 +18,7 @@
     'private',
     'http://localhost:8050'
 )
+server = app.server
 
 
 app.layout = html.Div([