Usage

This page is currently a placeholder and will be filled with lots of content over time.

Auditor ¶

See the tutorial page on the site for the attestation sub-project.

Updates ¶

The update system implements automatic background updates. It checks for updates approximately once every four hours when there's network connectivity and then downloads and installs updates in the background. It will pick up where it left off if downloads are interrupted, so you don't need to worry about interrupting it. Similarly, interrupting the installation isn't a risk because updates are installed to a secondary installation of GrapheneOS which only becomes the active installation after the update is complete. Once the update is complete, you'll be informed with a notification and simply need to reboot with the button in the notification or via a normal reboot. If the new version fails to boot, the OS will be rolled back to the past version and the updater will attempt to download and install the update again.

The updater will use incremental updates to download only changes rather than the whole OS unless the current version is behind the current release by more than 3 versions. As long as you have working network connectivity on a regular basis and reboot when asked, you'll almost always be on one of the past couple versions of the OS which will minimize bandwidth usage since incrementals will always be available. If you fall more than 3 versions behind, it will download a large full update shipping the full OS so it can update from any version.

The updater works while the device is locked / idle, including before the first unlock since it's explicitly designed to be able to run before decryption of user data.

Release changelogs are available in a section on the releases page.

Settings ¶

The settings are available in the Settings app in System ➔ Advanced ➔ Update settings.

The "Release channel" setting can be changed from the default Stable channel to the Beta channel if you want to help with testing. The Beta channel will usually simply follow the Stable channel, but the Beta channel may be used to experiment with new features.

The "Permitted networks" setting controls which networks will be used to perform updates. It defaults to using any network connection. It can be set to "Non-roaming" to disable it when the cellular service is marked as roaming or "Unmetered" to disable it on cellular networks and also Wi-Fi networks marked as metered.

The "Require battery above warning level" setting controls whether updates will only be performed when the battery is above the level where the warning message is shown. The standard value is at 15% capacity.

Enabling the opt-in "Automatic reboot" setting allows the updater to reboot the device after an update once it has been idle for a long time. When this setting is enabled, a device can take care of any number of updates completely automatically even if it's left completely idle.

Security ¶

The update server isn't a trusted party since updates are signed and verified along with downgrade attacks being prevented. The update protocol doesn't send identifiable information to the update server and works well over a VPN / Tor. GrapheneOS isn't able to comply with a government order to build, sign and ship a malicious update to a specific user's device based on information like the IMEI, serial number, etc. The update server only ends up knowing the IP address used to connect to it and the version being upgraded from based on the requested incremental.

Android updates can support serialno constraints to make them validate only on a certain device but GrapheneOS rejects any update with a serialno constraint for both the Stable and Beta channels.

Disabling ¶

It's highly recommended to leave automatic updates enabled and to configure the permitted networks if the bandwidth usage is a problem on your mobile data connection. However, it's possible to turn off the update client by going to Settings ➔ Apps, enabling Show system via the menu, selecting Seamless Update Client and disabling the app. If you do this, you'll need to remember to enable it again to start receiving updates.

Default connections ¶

GrapheneOS makes connections to the outside world to test connectivity, detect captive portals and download updates. No data varying per user / installation is sent in these connections. There aren't analytics / telemetry in GrapheneOS.

The expected default connections by GrapheneOS (including all base system apps) are the following:

• The GrapheneOS Updater app fetches update metadata from https://seamlessupdate.app/DEVICE-CHANNEL approximately once every four hours when connected to a permitted network for updates.

  Users can control which types of connections the Updater app will use, and although it's strongly recommended to always leave it enabled it can be disabled.

• On devices with a Qualcomm baseband (which provides GPS), when location functionality is being used, GPS almanacs are downloaded from https://xtrapath1.izatcloud.net/xtra3grc.bin, https://xtrapath2.izatcloud.net/xtra3grc.bin or https://xtrapath3.izatcloud.net/xtra3grc.bin. GrapheneOS has modified all references to these servers to use HTTPS rather than a mix of HTTP and HTTPS.

• Connectivity checks designed to mimic a web browser user agent are performed by using HTTP and HTTPS to fetch standard URLs generating an HTTP 204 status code. This is used to detect when internet connectivity is lost on a network, which triggers fallback to other available networks if possible. These checks are designed to detect and handle captive portals which substitute the expected empty 204 response with their own web page. These need use a very common domain and URL in order to bypass whitelisting systems only permitting access to common domains / URLs so a domain like grapheneos.org would likely be inadequate. GrapheneOS leaves these set to the standard four URLs to blend into the crowd of billions of other Android devices with and without Google Mobile Services performing the same empty GET requests. For privacy reasons, it isn't desirable to stand out from the crowd and changing these URLs or even disabling the feature will likely reduce your privacy by giving your device a more unique fingerprint. GrapheneOS aims to appear like any other common mobile device on the network.

  • HTTPS: https://www.google.com/generate_204
  • HTTP: http://connectivitycheck.gstatic.com/generate_204
  • HTTP fallback: http://www.google.com/gen_204
  • HTTP other fallback: http://play.googleapis.com/generate_204

  Standard AOSP user agent for the GET request:

  Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.32 Safari/537.36

  No query / data is sent and the response is unused beyond checking the response code.

• DNS connectivity and functionality tests

• DNS resolution for other connections

Similar connectivity checks are also performed by the hardened Chromium browser (Vanadium).