SECP256K1 curve encryption not working

[Hugo.Dev]

Hi, 

We are using ncs 2.4.0, working with a custom project based in matter lock sample.

We were using SECP256R1 curves for encryption, without issues, but we need to move to SECP256K1, and we are getting MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE error when trying to sign a message. 

Going deeper I´ve found the function returning error is mbedtls_ecdsa_sign, but AFAIU the implementation is within nrfxlib/nrf_security/src/libmbedcrypto.a

Then I cannot check why it is returning this error

I have already enabled MBEDTLS_ECP_DP_SECP256K1_ENABLED in config file.

Any help will be appreciated.

Hugo

[tfoobarq]

Any update on this issue?

I'm getting same -0x4E80 code running the example from /examples/crypto/nrf_crypto/ecdsa/pca10056/

I'm using the nRF5_SDK_17.1.0_ddde560 on nRF52840 DK, and in my sdk_config:

#ifndef NRF_CRYPTO_BACKEND_MBEDTLS_ECC_SECP256R1_ENABLED
#define NRF_CRYPTO_BACKEND_MBEDTLS_ECC_SECP256R1_ENABLED 1
#endif

[tfoobarq]

OK, the error is caused by nrf_crypto_backend_mbedtls_ecc_mbedtls_rng, which directly returns -0x4e80 for the default config.

But I can't see where to enable this module?

[tfoobarq]

OK I solved my case with this setting. 

// <i> The nRF HW backend provide access to RNG peripheral in nRF5x devices.
//==========================================================
#ifndef NRF_CRYPTO_BACKEND_NRF_HW_RNG_ENABLED
#define NRF_CRYPTO_BACKEND_NRF_HW_RNG_ENABLED 1
#endif
// <q> NRF_CRYPTO_BACKEND_NRF_HW_RNG_MBEDTLS_CTR_DRBG_ENABLED  - Enable mbed TLS CTR-DRBG algorithm.
 

// <i> Enable mbed TLS CTR-DRBG standardized by NIST (NIST SP 800-90A Rev. 1). The nRF HW RNG is used as an entropy source for seeding.

#ifndef NRF_CRYPTO_BACKEND_NRF_HW_RNG_MBEDTLS_CTR_DRBG_ENABLED
#define NRF_CRYPTO_BACKEND_NRF_HW_RNG_MBEDTLS_CTR_DRBG_ENABLED 1
#endif