# `NervesHubLink.Configurator.TPM`
[🔗](https://github.com/nerves-hub/nerves_hub_link/blob/v2.12.0/lib/nerves_hub_link/configurators/tpm.ex#L6)

Configurator enabling authentication via TPM.

If your project is using a [TPM](https://en.wikipedia.org/wiki/Trusted_Platform_Module), and
the [TPM](https://hex.pm/packages/tpm) Hex library, you can tell `NervesHubLink` to read the key
and certificate from the module and assign the SSL options for you by adding it as a dependency:

    def deps() do
      [
        {:tpm, "~> 0.2.0"}
      ]
    end

This allows your config to be simplified to:

    config :nerves_hub_link,
      host: "your.nerveshub.host"

The TPM integration defaults include:
- initializing the modprobe `tpm_tis_spi`
- reading the private key using the path `/data/.ssh/nerves_hub_link_key`
- restoring the private key from the TPM, using the memory address `"0x1000000"`, if it isn't found on the filesystem
- and reading the certificate from the memory address `"0x1000001"`

You can customize these options to use a different bus and certificate pair:

    config :nerves_hub_link, :tpm,
      probe_name: "tpm_tis_spi",
      key_path: "/data/.ssh"
      key_name: "nerves_hub_link_key",
      key_address: "0x1000000"
      certificate_address: "0x1000001"
      restore_key: true

---

*Consult [api-reference.md](api-reference.md) for complete listing*