I get your pc, “tamper” it, then i install a fake bios that tells you all is well and that your tpm and secureboot and whatever else bullcrap they invent is still happy.
A USB keylogger is not detectable by the computer, not in firmware nor operating system. It passively sniffs the traffic between the USB keyboard and the computer, to be dumped out later.
You know secure boot was specifically made to protect users for this exact use case. Any tampering of the system will prevent the system from booting.
I get your pc, “tamper” it, then i install a fake bios that tells you all is well and that your tpm and secureboot and whatever else bullcrap they invent is still happy.
See the problem?
It won’t boot though, because the keys to decrypt the system are stored in the TPM.
Sure you could replace the whole OS, but that’s going to be very obvious and won’t allow you access to the data.
Isnt it possible to have a recovery key? Isnt that technically a backdoor? Maybe the terms are not correct but there is a way in physically.
A person with physical access can tamper with the OS, then tamper with the signing keys. Most secure boot systems allow you to install keys.
Secure boot can’t detect a USB keylogger. Nothing can.
The signature checks will immediately fail if ANY tampering has occurred.
Adding a USB keylogger that has not been signed will cause a signature verification failure during boot.
A USB keylogger is not detectable by the computer, not in firmware nor operating system. It passively sniffs the traffic between the USB keyboard and the computer, to be dumped out later.
If your keys are stored in the TPM for use during the secure boot phase, there will be nothing for it to log.