% tpm2_policycountertimer(1) tpm2-tools | General Commands Manual

NAME

tpm2_policycountertimer(1) - Enables policy authorization by evaluating the comparison operation on the TPM parameters time, clock, reset count, restart count and TPM clock safe flag.

SYNOPSIS

tpm2_policycountertimer [OPTIONS] [ARGUMENT]

DESCRIPTION

tpm2_policycountertimer(1) - Enables policy authorization by evaluating the comparison operation on the TPM parameters time, clock, reset count, restart count and TPM clock safe flag. If time/clock, it is input as milliseconds value. The parameter and the value is given as a command line argument as below:

tpm2_policycountertimer -S session.ctx safe
tpm2_policycountertimer -S session.ctx clock=<N ms>
tpm2_policycountertimer -S session.ctx time=<N ms>
tpm2_policycountertimer -S session.ctx resets=<N>
tpm2_policycountertimer -S session.ctx restarts=<N>

By default comparison tests for equality and also by default it tests for time.

OPTIONS

  • -L, --policy=FILE:

    File to save the policy digest.

  • -S, --session=FILE:

    The policy session file generated via the -S option to tpm2_startauthsession or saved off of a previous tool run.

  • --eq

    if value of current time in the TPM = value of specified input time.

  • --neq

if value of current time in the TPM != value of specified input time.

  • --sgt

if signed value of current time in the TPM > signed value of specified input time.

  • --ugt

if unsigned value of current time in the TPM > unsigned value of specified input time.

  • --slt

if signed value of current time in the TPM < signed value of specified input time.

  • --ult

if unsigned value of current time in the TPM < unsigned value of specified input time.

  • --sge

if signed value of current time in the TPM >= signed value of specified input time.

  • --uge

if unsigned value of current time in the TPM >= unsigned value of specified input time.

  • --sle

if signed value of current time in the TPM <= unsigned value of specified input time.

  • --ule

if unsigned value of current time in the TPM <= unsigned value of specified input time.

  • --bs

    if all bits set in value of current time in the TPM are set in value of specified input time.

  • --bc

    if all bits set in value of current time in the TPM are clear in value of specified input time.

References

common options collection of common options that provide information many users may expect.

common tcti options collection of options used to configure the various known TCTI modules.

EXAMPLES

Create a sealing object with an authorization policy that evaluates only for first minute of TPM restart.

Create the policy and the sealing object

tpm2_startauthsession -S session.ctx

tpm2_policycountertimer -S session.ctx -L policy.countertimer --ult 60000

tpm2_flushcontext session.ctx

tpm2_createprimary -C o -c prim.ctx -Q

echo "SUPERSECRET" | \
tpm2_create -Q -u key.pub -r key.priv -i- -C prim.ctx \
-L policy.countertimer -a "fixedtpm|fixedparent" -c key.ctx

Unsealing should work in the first minute after TPM restart

tpm2_startauthsession -S session.ctx --policy-session

tpm2_policycountertimer -S session.ctx --ult 60000

tpm2_unseal -c key.ctx -p session:session.ctx

tpm2_flushcontext session.ctx

returns

limitations

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