On 1/12/2015 4:24 PM, Bill Martin wrote:
> I am using trouSerS 0.3.10 and have an Infineon TPM running 1.2 on an
> embedded Linux system.
>
> I have a system where I use tpm-luks scripts to retrieve a LUKS key
> from TPM NVRAM and decrypt the root partition (while running in
> initramfs). This uses the tpm_nvread command. On top of this I added
> code to create a AIK, unregister any previous AIK (into a throwaway
> key handle), and register the new AIK. Also I have another program to
> activate the AIK (first loading the AIK by UUID then call the
> Tspi_TPM_ActivateIdentity command.
>
> This works well...
>
> Until I reboot the computer with this TPM. The tpm_nvread command
> complains it cannot decrypt the file. It's that message about PCR
> does not match or something.

At the TPM layer, there is no tpm_nvread command.  Can you translate 
your command sequence into the TPM commands.

An NV read will not decrypt a file.  It might go as far as reading the 
decryption key from NV, although there might be some levels of 
indirection there as well.
>
> It seems I have to do a pkill -9 tcsd and then a tcsd -f & prior to
> rebooting so that the tpm_nvread succeeds.

It would be helpful to know the NV read error return.

It would also be helpful to have a dump of the NV public area to see 
what the read authorizations are.

>
> I wonder if anyone can explain why this is necessary. The PCRs don't
> seem to be changed. Somehow I suspect the AIK creation does something
> funny with the PCRs.

Have you actually read the PCRs during the failing case and success case?

A typical AIK creation should not affect PCRs.



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