TLS (Transport Layer Security) is used to secure IoT devices through encrypted communications. In this case embedded hardware must use light weight libraries and have a proper way to manage recourses.Use the same secure key storage methods and secure elements (e.g., ATECC608A) to ensure that you cannot extract your private keys.

Ensure you are using the latest cipher suites (e.g., AES, ECC), and that you have a complete certificate validation process to help prevent MITMs. Handshakes in TLS require a large amount of resources therefore re-use sessions where possible and reduce the number of reconnections may help to save resources.

The purpose is not just encryption but also authentication and integrity of the device only communicating with authenticated servers.

Securing Your IoT Device: Implementing TLS on Embedded Hardware