[BOUNTY] Support Play Integrity over remote DroidGuard + Server/Guide [$85]

Play Integrity should be supported over the remote DroidGuard functionality and there should be documentation how to set up a phone as a DroidGuard server.

Why?
While existing solutions allow getting a sufficiently passing Play Integrity token with a non-integrity-compliant device, there is the following problems that come with it:

• the requirement for a rooted phone,
• running the integrity-checking code from google on your phone that's purposefully obfuscated and fetched at runtime,
• running strange bypassing software with root permissions, like the closed-source TrickyStore and
• all of this has to permanently be kept up-to-date in line with updates to Play Integrity to stay passing

This is tedious, never-ending work that everyone rather avoids.
If you're a busy person it's also not really feasible. Imagine coming out of a cinema with your friends and heading for a rentable scooter only to realize you're device doesn't pass Play Integrity anymore.

If PI would work over another device, like an old, stock one you still have at home, it would fix these problems.
It would also open the oppurtunity for commercial integrity-attestation offerings, where you would like pay monthly and they then allow you to use their devices over a server which then serves valid integrity tokens to your device.

How to implement?

• Fix:

  remote droidguard currently does not work for play integrity due to play integrity using a multi step droidguard process and the implementation only supports single step (which is used by most other things that use droidguard).
  (https://github.com/microg/GmsCore/issues/2851#issuecomment-3435884995)

  • MAYBE SOLVED by https://github.com/microg/GmsCore/pull/3471 NOT VERIFIED YET though

• Write a remote DroidGuard server to handle the requests

  • NOT YET SOLVED, but probably soon at https://github.com/kaduvert/PlayIntegrityServer

• Create a guide/docs on how to set it up

  • PROBABLE SOLUTION AS OF 9/8/2026: it won't be that hard just flash the module and connect to it over the exposed port

• Either

  • make it run on stock phones (requires No-BL-Unlock rooting) or

  • create software that manages all the integrity-bypassing software on the custom-rom 'server device' so that it's always passes. as far as i know to make a custom phone pass you need:

    • microG / GApps
    • root solution (Magisk, KernelSU or similar)
    • PlayIntegrityFix or similar
    • TrickyStore or similar
      also i think the server can't just be some unpriviledged app or termux process since you have to spoof the client device environment a bit such that the environment doesnt differ too much (i think these tokens are like scoped to some app or whatever and it's like encoded in it who the token is for. you need to familiarize yourself with the internals a bit to really work out a proper concept here)

  • PROBABLE SOLUTION AS OF 9/8/2026: Since the solution is probably a Zygisk module, and there is AlwaysStrong now, i guess the "managing of all the integrity-bypassing software" is achieved by it but i didn't clearly debug a whole setup yet

This issue was edited because it was traced to being a Play Integrity issue at https://github.com/microg/GmsCore/issues/2851#issuecomment-3432997022.

See

1743924520.834 10285 20276 23037 W LocalRequestInterceptor: Error getting App Check token; using placeholder token instead. Error: com.google.firebase.FirebaseException: Error returned from API. code: 403 body: App attestation failed.
1743924521.066 10285 20276 23037 E FirebaseAuth: [SmsRetrieverHelper] SMS verification code request failed: unknown status code: 17499 Firebase App Check token is invalid.
1743924521.067 10285 20276 20276 D FirebaseAuth: Invoking original failure callbacks after phone verification failure for (my phone number), error - An internal error has occurred. [ Firebase App Check token is invalid. ]

Also if you're a BountyHounter:
Try everything you can to make it work, it's all good. Just know that most people who just set their AI to do it eventually turn up with garbage PRs, so you'll likely fail if you don't have killer AI or lots of clue yourself.
There's a reason this has a bounty on it. It's because it's not that easy.
Also if you feed all this into AI, including https://github.com/microg/GmsCore/pull/3575 in it's context window is highly recommended

Read the existing remote DroidGuard implementation and PR #3471 first, then verify whether multi-step Play Integrity works. Review the proposed PlayIntegrityServer and listed device requirements for the separate server work. Done requires verified Play Integrity support, a working remote DroidGuard server path, and a setup guide.