Public key derivation from Private Key (OpenSSL vs Bitcoin-Core)

[jlabbeKlavo]

Hi Team,

Currently trying to generate a secp256k1 public key from the same 32bytes private key on both openssl and bitcoin-core library.
So far, I have not been successful in creating 2x identical pubic keys.
I understand both openssl and bitcoin-core libraries are expecting big endian inputs.
Can you confirm those 2x libraries should produce the same output when given the same inputs?
Is there some material I can use as example?

I considered that the creation of the public key would create a different x and y (modular reduction seems to be used in bitcoin-core library, unsure about openssl) but potentially compatible and tested the signature/verification part:

• openssl signature / bitcoin-core verification
• bitcoin-core signature / openssl verification
  but at no success.

Thanks for your help.