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Rohde-Schwarz / TrustedGRUB2

DEPRECATED TPM enabled GRUB2 Bootloader
GNU General Public License v3.0
193 stars 77 forks source link

How to verify if kernel and ramdisk are modified illegally #46

Closed white00black closed 8 years ago

white00black commented 8 years ago

In version 1.3 with debug info, I can see that hash values of kernel and ramdisk are correct and have been written to PCR-10. However when I change kernel or ramdisk on purpose, the PCR-10 has been updated to a new value automatically and device still can boot successfully. I do not see the verification process to avoid the illegal change of kernel or ramdisk.

Am I wrong in somewhere?

neusdan commented 8 years ago

There is no such verification process. From the README:

Since the TPM is passive, it has no direct ability to check if the integrity of bootloader (and the OS kernel/modules and so on) actually is correct. This can only be done indirectly by using the seal/unseal functions of the TPM (for details on this topic, you should have a look at the TCG specifications or on other documents describing TCG/TPM abilities).