Using nrf_oberon for HMAC-SHA256 generation on nRF9160

[luc_eac]

I want to use the nrf_oberon library to generate HMAC-SHA256 hashes for my messages.

The SDK version that I am using is 1.5.0 and I am developing for the nRF9160 SiP. I have found the API description in the documentation: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.5.0/nrfxlib/crypto/doc/api.html#hmac-hash-based-aessage-authentication-code. This describes what the library does fine, however I can not for the life of me work out how to use the library.

(Which is a general problem for me with your documentation. It is driving me crazy..)

I have enabled the "Nordic security backend" through Kconfig, and have added "CONFIG_OBERON_BACKEND=y" to my config file, but I can not use the ocrypto_hmac_sha256_x functions described in the API. Nor can I find where the library lives, what header file to include containing the function prototypes and what options to set to actually configure and gain access to the oberon library.

Can you help me with this?

[Vidar Berg]

Hi,

This release you are using is becoming quite old now and there have been lot of changes made to the crypto support since then so I would not recommend it for new designs. I just wanted to mention this in case you are not forced to stay on this version. With that out of the way, for SDK 1.5.0 I would recommend you have a look at how the HMAC test case is implemented here: https://github.com/nrfconnect/sdk-nrf/tree/v1.5.0/tests/crypto. The Oberon library will be used as a backend to the mbedtls APIs if you build with the kconfig symbols defined in 'overlay-oberon.conf'.

Best regards,

Vidar