Google Messages

Questions
1

Hi folks,

Can anyone help me to better understand what I’m giving up when allowing Google Messages for RCS on GrapheneOS? Probably the most important part of my threat model is that I want to keep my communications as private as possible. This is 90% of why I’m still on iOS.

Thanks

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2

If you are coming from iOS it is important to understand that RCS messages are not yet guaranteed to be end to end encrypted (E2EE), as support for encryption depends on cell carriers, and as far as I know Apple has not yet implemented interoperable E2EE with RCS[1]. iMessagas on the other hand are guaranteed to use E2EE, provided that you are talking to another iOS user and you both have internet connectivity.

With regard to the specifics of using RCS on GrapheneOS, you may be best served by perusing some of the forum topic covering this on the GrapheneOS Forum. See also: Using RCS with Google Messages on GrapheneOS - GrapheneOS Discussion Forum

It has been a while since I have looked into this particular issue, but from what I remember, there are some specific extra permissions and potentially persistent identifying values you may need to expose to Google to get RCS working on GrapheneOS.

  1. Though I do believe that is in the works, and expected to come out soon. ↩︎

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E2EE RCS with iOS is coming quickly. It’s in iOS 26.5 public beta.

On GrapheneOS, it’s dependent on carrier. I’m most familiar with US carriers, which also likely will be one of the biggest RCS markets since people in other countries already default to another messenger for most of their communications (WhatsApp, Line, etc).

Verizon (and Verizon MVNOs) seems to be the most compatible. You just need to install play services, install Google messages from the play store, and enable the following minimum permissions for both:

  • Network
  • SMS
  • Phone
  • Contacts or contact scopes
  • Notifications (optional)

You may also need to go to Settings - Apps - Sandboxed Google Play - Google Settings - All Settings - Phone Number Verification. Then toggle it on to automatically verify it.

After this is all setup, open Google Messages, go to the settings menu, and confirm RCS is turned on and active. If it’s not (it usually isn’t), restart the phone. Restarting your device is a way to force Google to verify your number. It should work now.

For other carriers, follow the same steps. But before you start, open Settings - Apps - Sandboxed Google Play - Play services special permissions. Then toggle on Allow ICC authentication with device identifiers. (This does send Google some data about your device, but is unfortunately necessary for RCS on same carriers).

RCS will only work on the Owner profile by the way. You do not need to sign into Google, but you likely need to have the app installed from the play store, not the Aurora Store.

Optional:

If you don’t want to sign in to a Google account on your owner profile, a solution is to first install Google Messages from the Aurora Store. Then sign into the play store on another profile or private space and install Google Messages there. You do not need to grant any permissions and can disable it immediately after installing. By installing it there, it will overwrite the Owner installed version and say that it’s installed from the Play Store. You’ll need to keep updating Google Messages from that second profile/private space.

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