Comments (4)
ReadPCRs
will return whatever the TPM gave you back:
Lines 151 to 180 in d331077
At a guess, it looks like your TPM responded to the command with a success response containing none of the PCRs.
This sounds like a hardware/firmware bug, though I will note that its not unusual to need to call this method multiple times to get a full set of PCRs. For example:
from go-tpm.
@lihanshang two questions:
- What happens if you only specify PCRs 0-7?
- What happens if you use the
sudo tpm2_pcrread
command fromtpm2-tools
(Github Link, Centos Package).
from go-tpm.
From TPM Spec, Part 3: 22.4 TPM2_PCR_Read
The returned list may be empty if none of the selected PCR are implemented.
It sounds like only the SHA1 PCRs are currently implemented/enabled on your system. Typically, there is a BIOS option to toggle which banks are enabled. Can you check to see if your BIOS settings have some options for this?
from go-tpm.
Hey Guys.
Thanks for your replies and I have some update:
So after I read the PCRs using SHA1, I was able to read using SHA256. To reproduce this I reboot the machine and try using SHA256 and it stopped working. It is like using SHA1 trigger something for SHA256.
Any idea about this behaviour?
Plus: I am using centos 7 with only tpm2-tools 3.x version on it. This is a remote host that I may not be able to check the BIOS.
Thank you very much!
from go-tpm.
Related Issues (20)
- reduce repetitive, nested structs by proving a defaults package HOT 1
- support passing []byte as TPM2B HOT 2
- Add a Compare function
- Load TSS2 Private Key generated with tpm2tss-genkey HOT 2
- Inconsistency between written and read values when accessing PCR HOT 3
- reduce unnecessary overhead of Tbsi_Get_TCG_Log HOT 1
- Missing ExtraData in Quote
- Use `crypto/ecdh` for tpmdirect HOT 5
- Darwin ? HOT 1
- EvictControl missing from new tpm2 HOT 10
- Consider an UnmarshalReader API for types
- HMAC Session not working HOT 2
- Support As(TPMRC) for format-1 errors.
- Support serialization of persistent handles HOT 1
- Support for RSAEncrypt and RSADecrypt commands HOT 1
- TPM Simulator reporting unrecognised command over socket
- Implement TPM2_HMAC_Start
- New Releases ?! HOT 7
- missing Name for 'SignHandle' parameter HOT 2
- cmdAuths not respecting auth value HOT 1
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from go-tpm.