.. zephyr:code-sample:: persistent_key
:name: PSA Crypto persistent key
Manage and use persistent keys via the PSA Crypto API.
Overview
********
This sample demonstrates usage of persistent keys in the :ref:`PSA Crypto API <psa_crypto>`.
Requirements
************
In addition to the PSA Crypto API, an implementation of the
`PSA Internal Trusted Storage (ITS) API <https://arm-software.github.io/psa-api/storage/1.0/overview/architecture.html#the-internal-trusted-storage-api>`_
(for storage of the persistent keys) must be present for this sample to work.
It can be provided by:
* :ref:`tfm`, for ``*/ns`` :term:`board targets<board target>`.
* The :ref:`secure storage subsystem <secure_storage>`, for the other board targets.
Building
********
This sample is located in :zephyr_file:`samples/psa/persistent_key`.
Different configurations are defined in the :file:`sample.yaml` file.
You can use them to build the sample, depending on the PSA ITS provider, as follows:
.. tabs::
.. tab:: TF-M
For board targets with TF-M:
.. zephyr-app-commands::
:zephyr-app: samples/psa/persistent_key
:tool: west
:goals: build
:board: <ns_board_target>
:west-args: -T sample.psa.persistent_key.tfm
.. tab:: secure storage subsystem
For board targets without TF-M.
If the board target to compile for has an entropy driver (preferable):
.. zephyr-app-commands::
:zephyr-app: samples/psa/persistent_key
:tool: west
:goals: build
:board: <board_target>
:west-args: -T sample.psa.persistent_key.secure_storage.entropy_driver
Or, to use an insecure entropy source (only for testing):
.. zephyr-app-commands::
:zephyr-app: samples/psa/persistent_key
:tool: west
:goals: build
:board: <board_target>
:west-args: -T sample.psa.persistent_key.secure_storage.entropy_not_secure
To flash it, see :ref:`west-flashing`.
API reference
*************
`PSA Crypto key management API reference <https://arm-software.github.io/psa-api/crypto/1.2/api/keys/index.html>`_
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