Migration from micro_ecc to oberon backend for ECDSA. Signature verification failure.

[Valerii_Ie]

Hi, 
I'm using code based on sdk/components/libraries/bootloader/dfu/ for ECDSA verification of the signature. But switched to Oberon crypto backend. The signature was successfully verified with micro ecc but fails with Oberon. 
I suspect next can be the root cause: 

// <q> NRF_CRYPTO_BACKEND_MICRO_ECC_LITTLE_ENDIAN_ENABLED - Enable non-standard little endian byte order.

// <i> This affects parameters for all ECC API (raw keys, signature, digest, shared secret). Only for use in nRF SDK DFU!

#ifndef NRF_CRYPTO_BACKEND_MICRO_ECC_LITTLE_ENDIAN_ENABLED
#define NRF_CRYPTO_BACKEND_MICRO_ECC_LITTLE_ENDIAN_ENABLED 0
#endif

Please suggest the possible solution?

[Vidar Berg]

Hi,

I agree that it's likely related to endianness. I look into this, but please let me know what nRF5 SDK version you use so I'm sure we are looking at the same implementation. 

Thanks,

Vidar

[Valerii_Ie]

Hi Vidar, I'm working with sdk v. 15.0. 

[Vidar Berg]

Hi,

Thanks for confirming. I found this listed under known issues in the releases notes for SDK 15.0.0:

   Changing the backend for nrf_crypto in sdk_config.h alone is not sufficient
   because the relevant files are not included in the build and include paths.
   See the Migration Guide for a walkthrough of changing from the µECC to the
   Oberon backend.

And here is the section of the migration document that it's referring to: Porting from µECC to nrf_oberon.

Please make sure you have followed the migration steps outlined in the documentation I linked to above, particularly step 6 which reverses the endianness.

[Valerii_Ie]

Thanks! verified 
The corrected link is https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v15.0.0%2Fmigration.html&anchor=migr_dfu_crypto_oberon

[RVM]

Hi Valeri,

Is there any specific reason why you are migrating from uECC to OBERON for your ECDSA requirement?

Cheers

RMV