How to generate hmac-sha256 with sdk12.3.0 ?

RE: How to generate hmac-sha256 with sdk12.3.0 ?

swetha Paladugu — Thu, 19 Nov 2020 11:16:20 GMT

Thanks for your information Jorgen.

RE: How to generate hmac-sha256 with sdk12.3.0 ?

Jørgen Holmefjord — Thu, 19 Nov 2020 10:58:30 GMT

Yes, typically software takes longer time than hardware implementations. Also note that the Cortex M0 of nRF51 series ICs runs at 16 MHz, which will make the software operations 4 times slower than for instance nRF52 series running at 64 MHz.

RE: How to generate hmac-sha256 with sdk12.3.0 ?

swetha Paladugu — Thu, 19 Nov 2020 09:41:04 GMT

Ok i am using open source sha2.c/h files and i am able to generate hmac succesfully..

I am using this software hmac in my code for totp computations, i see that the computations are taking more time. Usually it happens with in a second.. Now i see that is taking more time..

Is it because we are doing everything in software, like this hmac?

Hardware crypto way of hmac generation would be faster right?

RE: How to generate hmac-sha256 with sdk12.3.0 ?

Jørgen Holmefjord — Thu, 19 Nov 2020 09:28:12 GMT

Most likely it will be easier to use the sha2.c/h files from your opensource library, as the input structures for the function calls may be more aligned. The sha256.c/h files in the SDK also originates from an opensource repository, as mentioned in the header:

 *          This code is adapted from code by Brad Conte, retrieved from
 *          https://github.com/B-Con/crypto-algorithms.

RE: How to generate hmac-sha256 with sdk12.3.0 ?

swetha Paladugu — Thu, 19 Nov 2020 04:43:04 GMT

In opensource i got sha2.c and sha2.h files along with hmac.c and hmac.h files.

If i use the opensource library, is it necessary that i should sha256.c and sha256.h of nrf sdk 12.3.0 instead of sha2.c and sha2.h of opensource.. or can i use the open source sha2.c and sha2.h files directly?

What do u suggest?

Thanks,

Swetha.

RE: How to generate hmac-sha256 with sdk12.3.0 ?

Jørgen Holmefjord — Wed, 18 Nov 2020 16:33:00 GMT

Hi,

The cryptographic library in SDK 12.3.0 is very limited, and only supports SHA256 Hashing algorithm, not HMAC, see Library usage.

That being said, there is no HW cryptographic acceleration features on the nRF51 series, so any C embedded crypto library that can run on a ARM Cortex M0 CPU should be possible to integrate with your application.

Best regards,
Jørgen