Thank you for reply.
..ok, the function produces two digests.
Let's suppose to set pcrEvent in this way:
pcrEvent.eventType = (UINT32) 0;
pcrEvent.rgbEvent = (BYTE *) "Event information";
pcrEvent.ulEventLength = (UINT32) strlen((char *)pcrEvent.rgbEvent);
and extend PCR 16 previously reset:
UINT32 pcrIndex = 16;
char *data = "12345678901234567890";
UINT32 dataLen = strlen(data);
Tspi_TPM_PcrExtend(hTPM, pcrIndex, dataLen, (BYTE *)data, &pcrEvent, \
&pcrValueLen, &pcrValue);
I get this from pcrEvent.rgbPcrValue:
D5 77 EA 60 0E 25 58 83 C3 7A 9B 67 AC 4E C4 7E 72 B1 97 CA
and this from pcrValue:
DD 41 DE 26 27 6A D0 CC AF 1F 7A 7A 0D 35 CA 8F 30 EF BD AC
What should I give in input to Tspi_Hash_UpdateHashValue() to obtain
these two digests?
I did expect to obtain pcrEvent.rgbPcrValue hashing this:
BYTE data[] = {
/* UINT32 pcrIndex 16 */ 0x00, 0x10, \
/* pcrData */ \
'1','2','3','4','5','6','7','8','9','0','1','2','3','4','5','6','7','8','9','0',\
/* UINT32 eventType */ 0, 0, \
/* rgbEvent */ \
'E','v','e','n','t',' ','i','n','f','o','r','m','a','t','i','o','n' };
but I get a different digest:
D0 49 5F 73 19 E8 91 53 5C 59 94 73 1F 76 19 EB 7F F7 1B 5E
(...and I did expect to obtain pcrValue hashing this:
20 0's (empty PCR 16) || pcrEvent.rgbPcrValue ...)
Thank you again,
Max
Il 10/06/2015 15:22, Ken Goldman ha scritto:
> At the TPM layer, the value to be extended must be exactly 20 bytes.
>
> I found this in the mailing list. I wonder if the code was fixed but
> that the documentation is still wrong. It looks like they removed the
> double hash, so you have to send 20 bytes.
>
> ~~
>
> Note that trousers-0.2.8's implementation of Tspi_TPM_PcrExtend is
> wrong, it has been updated to be correct in CVS, which will become
> 0.2.9.
>
> ~~
> If no PCR event structure is passed to Tspi_TPM_PcrExtend, the data
> passed to it will be sent directly to the TPM, without modification
> (meaning that anything but 20 bytes will get you TSS_E_BAD_PARAMETER).
> If there is a PCR event structure passed to Tspi_TPM_PcrExtend, the
> TSS will create a hash value using the data passed in and fields of
> the PCR event structure, like this: SHA1(ulPcrIndex | pbPcrData |
> pPcrEvent->eventType | pPcrEvent->rgbEvent). That hash will then be
> sent to the TPM and TCS_LogPcrEvent will be called to add the event to
> the log.
> ~~
>
> True, the trousers 0.2.8 mistakenly re-hashes the input to
> Tspi_TPM_PcrExtend. This is fixed in CVS though...
>
> On 6/9/2015 11:21 PM, Massimo Gaggiano wrote:
>> ..no error if pcrEvent != NULL and data size != 20.
>>
>> Is this regular?
>>
>> ------------------------------------------------------------------------
>> Da: Massimo Gaggiano <mailto:[email protected]>
>> Inviato: 08/06/2015 01:27
>> A: [email protected]
>> <mailto:[email protected]>
>> Oggetto: [TrouSerS-users] PcrExtend() explanation
>>
>> Hi all,
>> I use IBM Software TPM.
>>
>> If the param 'pPcrEvent' is NULL I get the error 3003 "Bad parameter"
>> when extending with data size different than 20.
>> (No error with "12345678901234567890")
>>
>> Is there something I'm ignoring?
>>
>> Thank you very much.
>> Max
>>
>> Here is my code in summary:
>>
>> const char *data = "s";
>> UINT32 dataLen = strlen(data);
>> Tspi_TPM_PcrExtend(hTPM, pcrIndex, dataLen, (BYTE *)data, NULL, \
>> &pcrValueLen, &pcrValue);
>
>
>
>
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