Earlier quoted context omitted.
> * Secure Boot (vendor-keyed deployments) I wish this myth would die at this point. Secure Boot allows you to enroll your own keys. This is part of the spec, and there are no shipped firmwares that prevents you from going through this process.
Android lets you put your own signed keys in on certain phones. For now. The banking apps still won't trust them, though. To add a quote from Lennart himself: "The OS configuration and state (i.e. /etc/ and /var/) must be encrypted, and authenticated before they are used. The encryption key should be bound to the TPM device; i.e system data should be locked to a security concept belonging to the system, not the user.…
The oppressive part of this scheme is that Google's integrity check only passes for _their_ keys, which form a chain of trust through the TEE/TPM, through the bootloader and finally through the system image. Crucially, the only part banks should care about should just be the TEE and some secure storage, but Google provides an easy attestation scheme only for the entire hardware/software environment and not just the secure hardware bit that already lives in your phone and can't be phished.
It would be freaking cool if someone could turn your TPM into a Yubikey and have it be useful for you and your bank without having to verify the entire system firmware, bootloader and operating system.