How to include the mbed library into the nrf9151 build using SDK 3.0.2?

marjonz

I have the following in my prj.conf

# MBED TLS for Authentication
CONFIG_MBEDTLS=y
CONFIG_MBEDTLS_BUILTIN=y

But that seems to still not link the necessary files from the mbed library, and during linking, I get:'

undefined reference to `mbedtls_md_info_from_type'
undefined reference to `mbedtls_md_init'
undefined reference to `mbedtls_md_setup'

Looks like the nRF has changed the way the crypto library should be linked, but I’ve been at it the whole day trying to find the right combination and still no success.

Any help/advice is very much appreciated.

jaredwolff

The modem has built in crypto. I assume it doesn’t support what you’re looking for? It does have limited ciphers compared to mbed.

I’m not near my computer but there’s also a kconfig that switches whether or not it’s offloaded to the modem or using Mbed. That’s probably the key there.

I would look at some of the applications and samples in nrf. I bet you’ll find it.

marjonz

I have, but none of the prj.conf or Kconfig settings related to mbed seem to work. The mbed functions I am trying to call in my code seems to still be missing from the compile, or that an additional compiler option is missing.

I am directly calling the mbed functions for my application.

jaredwolff

It’s failing because you need to be calling the Zephyr native socket/crypto mechanisms. Depending on how things are configured, Zephyr will use the crypto backend that was chosen.

marjonz

To close this thread and for the next person, add the following lines in your prj.conf:

# MBED TLS for Authentication
CONFIG_MBEDTLS=y
CONFIG_MBEDTLS_MD_C=y
CONFIG_MBEDTLS_SHA256_C=y
CONFIG_NRF_SECURITY=y
CONFIG_NORDIC_SECURITY_BACKEND=y

It will use a precompiled mbedtls library and link that and then I was able to use the functions in the

#include <mbedtls/base64.h>
#include <mbedtls/md.h>

headers. Thanks 🙂