Added fundaments of SecretStorage vault

This class will handle the storing and processing
of secrets. Such as tokens. It will try to use the system
keyring by default. Falling back to less secure methods,
if the user doesn't allow access to the keyring or if
the back-end is unsupported.

CURA-7180 keyring storage

cura/OAuth2/AuthorizationService.py

@@ -17,7 +17,8 @@ from UM.i18n import i18nCatalog
 from cura.OAuth2.AuthorizationHelpers import AuthorizationHelpers, TOKEN_TIMESTAMP_FORMAT
 from cura.OAuth2.LocalAuthorizationServer import LocalAuthorizationServer
 from cura.OAuth2.Models import AuthenticationResponse
-import keyring
+from cura.OAuth2.SecretStorage import SecretStorage
+
 i18n_catalog = i18nCatalog("cura")
 
 if TYPE_CHECKING:
@@ -52,6 +53,8 @@ class AuthorizationService:
 
         self.onAuthStateChanged.connect(self._authChanged)
 
+        self._secret_storage = SecretStorage()
+
     def _authChanged(self, logged_in):
         if logged_in and self._unable_to_get_data_message is not None:
             self._unable_to_get_data_message.hide()
@@ -232,7 +235,7 @@ class AuthorizationService:
 
             # Since we stored all the sensitive stuff in the keyring, restore that now.
             # Don't store the access_token, as it's very long and that (or tried workarounds) causes issues on Windows.
-            preferences_data["refresh_token"] = keyring.get_password("cura", "refresh_token")
+            preferences_data["refresh_token"] = self._secret_storage["refresh_token"]
 
             if preferences_data:
                 self._auth_data = AuthenticationResponse(**preferences_data)
@@ -263,7 +266,8 @@ class AuthorizationService:
 
             # Store all the sensitive stuff in the keyring
             # Don't store the access_token, as it's very long and that (or tried workarounds) causes issues on Windows.
-            keyring.set_password("cura", "refresh_token", auth_data.refresh_token)
+            self._secret_storage["refresh_token"] = auth_data.refresh_token
+
 
             # And remove that data again so it isn't stored in the preferences.
             # Keep the access_token, as it's very long and that (or tried workarounds) causes issues on Windows.
@@ -275,4 +279,3 @@ class AuthorizationService:
             self._preferences.resetPreference(self._settings.AUTH_DATA_PREFERENCE_KEY)
 
         self.accessTokenChanged.emit()
-

cura/OAuth2/SecretStorage.py

@@ -0,0 +1,20 @@
+import keyring
+
+
+class SecretStorage:
+    def __init__(self):
+        self._stored_secrets = []
+
+    def __delitem__(self, key):
+        if key in self._stored_secrets:
+            del self._stored_secrets[key]
+            keyring.delete_password("cura", key)
+
+    def __setitem__(self, key, value):
+        self._stored_secrets.append(key)
+        keyring.set_password("cura", key, value)
+
+    def __getitem__(self, key):
+        if key in self._stored_secrets:
+            return keyring.get_password("cura", key)
+        return None