Crypto: HKDF

The HMAC Key Derivation Function (HKDF) sample shows how to derive keys with the HKDF algorithm, using a sample key, salt, and additional data.

Overview

The sample follows these steps:

1. First, the sample initializes the Platform Security Architecture (PSA) API.

2. Then, it performs key derivation:

   1. The input key is imported into the PSA crypto keystore.

   2. The output key is derived.

3. Afterwards, it performs cleanup:

   1. The input and the output keys are removed from the PSA crypto keystore.

Requirements

The sample supports the following development kits:

Hardware platforms	PCA	Board name	Build target
nRF5340 DK	PCA10095	nrf5340dk_nrf5340	nrf5340dk_nrf5340_cpuapp_ns
nRF5340 DK	PCA10095	nrf5340dk_nrf5340	nrf5340dk_nrf5340_cpuapp
nRF9160 DK	PCA10090	nrf9160dk_nrf9160	nrf9160dk_nrf9160_ns
nRF9160 DK	PCA10090	nrf9160dk_nrf9160	nrf9160dk_nrf9160
nRF52840 DK	PCA10056	nrf52840dk_nrf52840	nrf52840dk_nrf52840

When built for nrf5340dk_nrf5340_cpuapp_ns and nrf9160dk_nrf9160_ns targets, the sample is configured to compile and run as a non-secure application. Therefore, it automatically includes TF-M that prepares the required peripherals to be available for the application.

Building and running

This sample can be found under samples/crypto/hkdf in the nRF Connect SDK folder structure.

See Building and programming an application for information about how to build and program the application.

Testing

After programming the sample to your development kit, test it by performing the following steps:

1. Connect to the kit with a terminal emulator (for example, PuTTY). See How to connect with PuTTY for the required settings.

2. Compile and program the application.

3. Observe the logs from the application using an RTT Viewer or a terminal emulator.

Note

By default, the sample is configured to use both RTT and UART for logging. If you are using RTT, skip the first step of the testing procedure.