Play Integrity API has no minimum security patch level and nearly all these apps use weak software-based checks that are easily bypassed by attackers. The hardware-based checks rely on trusting every key distributed to every certified Android device, which are often leaked.

Hardware-based attestation can be used for security purposes such as verifying device integrity with a pinning-based approach without the weakness of being vulnerable to leaked keys from the whole Android ecosystem since specific per-app keys in the secure element can be pinned.

Play Integrity API is claimed to be based on devices complying with the Compatibility Test Suite and Compatibility Definition Document. We have irrefutable proof that the majority of certified Android devices do not comply with the CTS/CDD. Play Integrity API is based on lies.

Essentially every non-Pixel device has important CTS failures not caused by CTS bugs. OEMs are cheating to obtain certification. Google claims GrapheneOS can't be permitted because we don't have a certification where they freely allow cheating and don't ban non-compliant devices.

Since Play Integrity doesn't even have a minimum security patch level, it permits a device with multiple years of missing patches. Hardware attestation was required on all devices launched with Android 8 or later, but they don't enforce it to permit non-compliant devices.

The reality is that the Play Integrity API permits devices from companies partnered with Google with privileged Google Play integration when they're running the stock OS. It's easy to bypass, but they'll make changes to block it being done at scale long term such as if we did it.

It does not matter if these devices have years of missing security patches. It doesn't matter if the companies skipped or improperly implemented mandatory security features despite that being required by CDD compliance. Failing even very important CTS tests doesn't matter either.

Google can either permit GrapheneOS in the Play Integrity API in the near future via the approach documented at https://grapheneos.org/articles/attestation-compatibility-guide or we'll be taking legal action against them and their partners. We've started the process of talking to regulators and they're interested.