Create RSA public / private key with OpenSSL?

The main problem is that I am fairly new to C and the OpenSSL documentation is not clear enough for me, I tried to use Reading and writing rsa keys to a pem file in C , but I don't quite understand it. For example, how create_rsa_key()

does a function create both private and public? And where does it come from pCipher

? And what is the point pcszPassphrase

?

I'll explain that this is some kind of pseudocode, this is what I want to do, and the ones in bold are the ones I don't know how to do:

• generate private key and public key as buffers in hex (client)
• it is safe (public) to publish the key to another endpoint
• encrypt some data with a random 256-bit password using AES256 CBC (server)
• encrypt password with public key (server)
• send encrypted data to client (server)
• decrypt encrypted 256-bit password with private key (client)
• decrypt file

Basically I know how to handle AES encryption / decryption and communication protocol, they are already implemented anyway, my problem is RSA and I need not base64 or pem hex as I work with sockets and also send and store as binary data.