nRF9160DK Keccak256 ECDSA SAMPLE

RE: nRF9160DK Keccak256 ECDSA SAMPLE

Gioele — Mon, 05 Sep 2022 13:05:31 GMT

Okay, let's talk in the other case discussing!

RE: nRF9160DK Keccak256 ECDSA SAMPLE

Kenneth — Mon, 05 Sep 2022 12:39:46 GMT

I can see you already have an open case discussing the same, I suggest to continue there:
nRF9160 DK Ethereum Ecdsa "s problem"

Kenneth

RE: nRF9160DK Keccak256 ECDSA SAMPLE

Gioele — Mon, 05 Sep 2022 10:04:47 GMT

We understood that the Keccack256 function is not supported we implemented third party library but we noticed that for some values the ECDSA result is wrong related to the "s value".
We noticed that when we make the Keccak256 of a standard number or a text the "r and s values" are correct, but when we make the keccack256 of RLP only the "r value" is correct.

RE: nRF9160DK Keccak256 ECDSA SAMPLE

Kenneth — Mon, 05 Sep 2022 08:00:38 GMT

You can find an overview of the crypto samples and tests supported in our nRF Connect SDK here:
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/tests/crypto/README.html

If it's not listed there you will need to implement third party library and check their documentation on test and usage.

Kenneth

RE: nRF9160DK Keccak256 ECDSA SAMPLE

Gioele — Fri, 02 Sep 2022 13:56:42 GMT

We are doing exactly this. We are sure that the keccak256 is correct in hex but the final result is not correct (the "s value")

RE: nRF9160DK Keccak256 ECDSA SAMPLE

Emil Lenngren — Thu, 01 Sep 2022 22:02:20 GMT

You can use any external library for calculating Keccak-256. A quick search gave me this: https://github.com/firefly/wallet/blob/master/source/libs/ethers/src/keccak256.c. That replaces psa_hash_compute.

You should be able to keep the psa_sign_hash call as it is. In contrary to RSA which includes the hash aglorithm used as part of the signature, this is not done in ECDSA. So you should be able to pass PSA_ALG_DETERMINISTIC_ECDSA(PSA_ALG_SHA_256) there without any issues.