Issue in Compatibilty with uECC and openssl

[Mathangopal]

Hi. I am trying to generate a shared key via ECDH to encrypt message through UART between nrf52832 and Qualcomm chip. nRF52832 is using uECC and Qualcomm is using openssl. However, the generated shared key on nrf side and Qualcomm chip side is different. I tried using the same private and public key on both side and it is still generating two different shared key. Is uECC compatible with openssl? I will appreciate the help given.

[Vidar Berg]

Hi,

uECC is built to work with little-endian keys while openssl is big endian so that's probably the biggest difference. I have not tried to work with openssl myself but looks like it should be possible to make the keys compatible according to the discussion here: https://githubmemory.com/repo/kmackay/micro-ecc/issues/173

Best regards,

Vidar

[Mathangopal]

Hi. Do you have any other library that works with openssl? Seems like there is a lot of issues with uECC. I can also use uECC library on the Qualcomm chip. I am using uECC_set_rng(&RAND_bytes) with the same private and public key however, the shared key is still different. RAND_bytes is a openssl random bytes generator is this compatible with the nrf random number generator? if no, can you share a random number generator function that I can use which is compatible with nrf.