-        if not self._device_id or not self._device_token:
-            device = self._downloader.cache.load('cbcwatch', 'device') or {}
-            self._device_id, self._device_token = device.get('id'), device.get('token')
-            if not self._device_id or not self._device_token:
-                result = self._download_xml(
-                    self._API_BASE_URL + 'device/register',
-                    None, data=b'<device><type>web</type></device>')
-                self._device_id = xpath_text(result, 'deviceId', fatal=True)
-                self._device_token = xpath_text(result, 'deviceToken', fatal=True)
-                self._downloader.cache.store(
-                    'cbcwatch', 'device', {
-                        'id': self._device_id,
-                        'token': self._device_token,
-                    })
+        if self._valid_device_token():
+            return
+        device = self._downloader.cache.load(
+            'cbcwatch', self._cache_device_key()) or {}
+        self._device_id, self._device_token = device.get('id'), device.get('token')
+        if self._valid_device_token():
+            return
+        self._register_device()
+
+    def _valid_device_token(self):
+        return self._device_id and self._device_token
+
+    def _cache_device_key(self):
+        email, _ = self._get_login_info()
+        return '%s_device' % hashlib.sha256(email.encode()).hexdigest() if email else 'device'
+
+    def _register_device(self):
+        result = self._download_xml(
+            self._API_BASE_URL + 'device/register',
+            None, 'Acquiring device token',
+            data=b'<device><type>web</type></device>')
+        self._device_id = xpath_text(result, 'deviceId', fatal=True)
+        email, password = self._get_login_info()
+        if email and password:
+            signature = self._signature(email, password)
+            data = '<login><token>{0}</token><device><deviceId>{1}</deviceId><type>web</type></device></login>'.format(
+                escape(signature), escape(self._device_id)).encode()
+            url = self._API_BASE_URL + 'device/login'
+            result = self._download_xml(
+                url, None, data=data,
+                headers={'content-type': 'application/xml'})
+            self._device_token = xpath_text(result, 'token', fatal=True)
+        else:
+            self._device_token = xpath_text(result, 'deviceToken', fatal=True)
+        self._downloader.cache.store(
+            'cbcwatch', self._cache_device_key(), {
+                'id': self._device_id,
+                'token': self._device_token,
+            })