Install micro-ecc with SEGGER

RE: Install micro-ecc with SEGGER

RVM — Mon, 25 Jan 2021 18:51:12 GMT

I have a follow up question.

I want to use the ECDSA256 with the micro-ecc but for the life of me I cannot get a fully linked build.

I keep getting this error in the bootloader:
nrf_dfu_validation.c:(.text.nrf_dfu_validation_signature_check+0x3e): undefined reference to `nrf_crypto_hash_calculate'

I have raised this issue in another ticket but wanted to see if you have any suggestions.
What kind of backend can I use to support ECDSA256 on nRF52832 (no 310), SDK 16.0.0 and S132 v7.0.2

Cheers

RMV

RE: Install micro-ecc with SEGGER

Jørgen Holmefjord — Thu, 09 Jul 2020 09:27:03 GMT

Hi,

Sorry for misunderstanding your question. SES uses GCC as the compiler internally. The libraries built by GCC can be used with SES.

You can see the backends supporting AES in the nrf_crypto library documentation. For nRF52832, only mbedTLS is available, as it does not have the CC310 HW Cryptocell module in the chip. For MD5, this is not supported by the nrf_crypto library at all. I believe this was decided to not implement because it is simple to do in SW and not that much used in small embedded systems. I see that mbedTLS has functions for calculating MD5 (external\mbedtls\library\md5.c), they are included in the nRF_Crypto examples and I think you should be able to call the API without any modifications.

Best regards,
Jørgen

RE: Install micro-ecc with SEGGER

Nick_RA — Thu, 09 Jul 2020 07:18:00 GMT

Hi. Yes I understand the licencing issue, and I was referring to the page you linked to which doesn't help because step 4 (which I quoted in my question) doesn't make any reference to SES. "Enter the subdirectory for the SoC and the toolchain that you are using to build your application" - there isn't a subdirectory for Segger.

Anyway, I probably asked the wrong question because I was just trying to compile the SDK examples to start with which maybe isn't the best approach here.

I need 2 crypto functions. AES encrypt/decrypt, and MD5 for file checking. What libraries do I need to include?

RE: Install micro-ecc with SEGGER

Jørgen Holmefjord — Tue, 07 Jul 2020 14:31:35 GMT

Hi,

We are not allowed to provide micro-ecc with the SDK due to limitations in the license of the library. If you want to use the micro-ecc backend, you need to build it yourself using GCC. See the instructions here.

By default, the micro-ecc backend is not used in the crypto examples, the nRF_Oberon backend is used (NRF_CRYPTO_BACKEND_OBERON_ENABLED=1). You can exclude/remove the micro-ecc library file (micro_ecc_lib_nrf52.a) from the project if you do not intend to use it. That way you should be able to build the examples in SES without any need for additional tools.

Best regards,
Jørgen