Missing getters on some fields

[sevilS]

Suggested enhancement

We need access to some of the fields that are now private since version 3.0.0:

mbedtls_pk_context
pk_ctx

mbedtls_ecp_keypair
d

###Justification

mbedtls_pk_context: We have to configure a pk_ctx in order to be able to implement ecdsa_alt functionality

mbedtls_ecp_keypair: Same, for ecdsa_alt functionality we need to provide the key information inside d field

[marcobrador]

Hi! Any update on this?

[mpg]

Hi! Thanks for your report. Could you clarify if you need read or write access to these fields?

Also, it's not clear to me if what you mean exactly by ecdsa_alt functionality. Are you talking about MBEDTLS_ECDSA_SIGN_ALT, MBEDTLS_ECDSA_VERIFY_ALT and/or MBEDTLS_ECDSA_GENKEY_ALT? If so:

1. I think it's quite normal for implementors of this function to use the MBEDTLS_PRIVATE macro in order to get access to private fields, and that doesn't mean these fields should be made public to everyone.
2. It's not clear to me why you need access to pk_ctx in mbedtls_pk_context_t for that, can you clarify?

[sevilS]

Hello!
i will try to explain our use case. We use ecdsa_alt functionality. But we don't need the private fields for the function itself, it is for the configuration steps.

In order to use it, we need some information that needs to be recovered in the sign method, this information is basically a key handle. We use the method mbedtls_mpi_read_binary((*mbedtls_ecp_keypair)keyPair->d, ourKeyHandle, ..); to do it.
That's why we need access to d field.

After this call we reassign the value:
(*mbedtls_pk_context_t).pk_ctx = keyPair;
If I am honest, looking at the mbedtls code, this last part is not required, as the method mbedtls_pk_ec is sending the same pointer we assign afterwards. But we need to get access to the d field for sure.

Thanks!