Managing Factory PKI

LmP devices connect to OTA services via a device gateway configured with mutual TLS. Each factory uses a default device gateway with certificates owned by We allow and encourage you to set up your own PKI infrastructure so that you are in control of the security of the device gateway.


Root of trust - factory_ca.key / factory_ca.pem

The PKI root of trust for your factory. You own the private key (NIST P-256 by default). The corresponding x509 certificate is shared with to define your root of trust.

All intermediate CA and mutual TLS certificates configured in your factory must be signed by this keypair. In particular, the certificates listed below.

Server TLS Certificate - tls-crt

This certificate along with its private key is used by Device Gateway during mTLS handshake/session setup. Specifically, they are used for Device Gateway identity verification by a device/client and a TLS session’s symmetric key setup. The private key is owned by and the certificate is signed by the root of trust.


In order for lmp-device-register to work, needs the ability to sign client certificates for devices. If enabled, the root of trust will sign an online-ca certificate that can use to sign client authentication certificates.


Optional pair(s) of a private key and intermediate CA certificate signed by the root CA that can be used by something like your manufacturing process sign client certificates for devices without needing access to

It is also known and referred as offline CA since a user owns its private key and keeps it “offline”.

PKI hierarchy

Setting up your PKI

Fioctl includes a sub-command to set this up: fioctl keys ca create /absolute/path/to/certs/. A few important things to note about this command:

  • It’s highly recommend that you use a PKCS#11 compatible HSM. This will ensure the safety of your factory’s root of trust private key.
  • The “PKI Directory” is important and should be securely backed up.

You can view the configured certificates with fioctl keys ca show --pretty.

The Factory PKI is interwoven with Device Manufacturing Process and Device Registration, you can find out more details on this topic in this guide Manufacturing Process for Device Registration.

More details on Factory PKI can be found in this guide.