% tpm2_nvreadlock(1) tpm2-tools | General Commands Manual

# NAME

**tpm2_nvreadlock**(1) - Lock the Non-Volatile (NV) index for further reads.

# SYNOPSIS

**tpm2_nvreadlock** [*OPTIONS*] [*ARGUMENT*]

# DESCRIPTION

**tpm2_nvreadlock**(1) - Lock the Non-Volatile (NV) index for further reads. The
lock on the NN index is unlocked when the TPM is restarted and the NV index
becomes readable again. The index can be specified as raw handle or an offset
value to the nv handle range "TPM2_HR_NV_INDEX".

# OPTIONS

  * **-C**, **\--hierarchy**=_OBJECT_:

    Specifies the hierarchy used to authorize.
    Supported options are:
      * **o** for **TPM_RH_OWNER**
      * **p** for **TPM_RH_PLATFORM**
      * **`<num>`** where a hierarchy handle or nv-index may be used.

    When **-C** isn't explicitly passed the index handle will be used to
    authorize against the index. The index auth value is set via the
    **-p** option to **tpm2_nvdefine**(1).

  * **-P**, **\--auth**=_AUTH_:

    Specifies the authorization value for the hierarchy.

  * **\--cphash**=_FILE_

    File path to record the hash of the command parameters. This is commonly
    termed as cpHash. NOTE: When this option is selected, The tool will not
    actually execute the command, it simply returns a cpHash.

  * **ARGUMENT** the command line argument specifies the NV index or offset
    number.

## References

[context object format](common/ctxobj.md) details the methods for specifying
_OBJECT_.

[authorization formatting](common/authorizations.md) details the methods for
specifying _AUTH_.

[common options](common/options.md) collection of common options that provide
information many users may expect.

[common tcti options](common/tcti.md) collection of options used to configure
the various known TCTI modules.

# EXAMPLES

## Lock an index
```bash
tpm2_nvdefine -Q   1 -C o -s 32 \
-a "ownerread|policywrite|ownerwrite|read_stclear"

echo "foobar" > nv.readlock

tpm2_nvwrite -Q   0x01000001 -C o -i nv.readlock

tpm2_nvread -Q   1 -C o -s 6 -o 0

tpm2_nvreadlock -Q   1 -C o
```

[returns](common/returns.md)

[footer](common/footer.md)