NAME

TPMLIB_SetState - Set the TPM's volatile, permanent, or save state

TPMLIB_GetState - Get the TPM's volatile, permanent, or save state

LIBRARY

TPM library (libtpms, -ltpms)

SYNOPSIS

#include <libtpms/tpm_library.h>

TPM_RESULT TPMLIB_SetState(enum TPMLIB_StateType st,
const unsigned char *buffer, uint32_t buflen);

TPM_RESULT TPMLIB_GetState(enum TPMLIB_StateType st,
unsigned char **buffer, uint32_t *buflen);

DESCRIPTION

The TPMLIB_SetState() function allows to set either one of the state blobs of the TPM. The passed state blob is tested for whether it can be accepted and a TPM error code is returned in case it cannot be accepted. In case of acceptance, the state blob will be passed to the TPM upon TPM_MainInit(). Setting a state blob hides a file that may contain the same type of blob and would be read otherwise. It is required to call this function with a NULL pointer for the buffer parameter to hide a state blob in a file.

It is only possible to set the state blobs after TPMLIB_ChooseTPMVersion() has been called. All state blobs are cleared when a different version of TPM is chosen using TPMLIB_ChooseTPMVersion or when a call to TPMLIB_SetState() fails because a state blob could not be accepted.

The order in which state blobs are set is important. The first state blob has to be the one representing the TPM's permanent state. Only after that either the volatile or save state blobs can be set.

The TPMLIB_GetState() function allows to get the current state of the TPM. For as long as the TPM has not been started, this function either returns the state blob previously set with TPMLIB_SetState() or the state is read from a file. Once the TPM has been start the state of the running TPM is returned.

The TPMLIB_STATE_SAVE_STATE (save state) type of TPM state can be set with this function. The same state blob will be returned until TPM_Startup(ST_STATE) has been called, after which an empty blob will be returned. This blob can also only be read after TPM_SaveState() has been sent to the TPM.

SEE ALSO

TPMLIB_ChooseTPMVersion(3), TPMLIB_MainInit(3), TPMLIB_Terminate(3)