Separating public and private keys from RSA keypair variable

Question

As the title says, I have some code that generates a pair of RSA keys. I want to split them apart and use them individually to encrypt/decrypt, rather than use the variable

Answer 1

I've found a solution to my question among other Stack-Overflow posts and namely Reading Public/Private Key from Memory with OpenSSL

The answer i was looking for is answered by @SquareRootOfTwentyThree is his last line of code,

After extracting the Public key into a BIO variable called pub:

PEM_write_bio_RSAPublicKey(pub, keypair);

i can send the variable pub across the network, and after it reaches the other side create a RSA variable and put pub inside it:

SOLUTION:

RSA *keypair2 = NULL; 
PEM_read_bio_RSAPublicKey( pub, &keypair2, NULL, NULL);

After i've done this i can successfully encrypt the message as usual, using keypair2:

ENCRYPTION:

encrypt = (char*)malloc(RSA_size(keypair));
int encrypt_len;
err = (char*)malloc(130);
if((encrypt_len = RSA_public_encrypt(strlen(msg)+1, (unsigned char*)msg,
        (unsigned char*)encrypt, keypair2 ,RSA_PKCS1_OAEP_PADDING)) == -1) {
    ERR_load_crypto_strings();
    ERR_error_string(ERR_get_error(), err);
    fprintf(stderr, "Error encrypting message: %s\n", err);
}

I can then send this encrypt variable back to the first machine, and decrypt it as usual, using my original keypair, without having to send it over the network.

DECRYPTION:

decrypt = (char*)malloc(encrypt_len);
if(RSA_private_decrypt(encrypt_len, (unsigned char*)encrypt, (unsigned char*)decrypt,
        keypair, RSA_PKCS1_OAEP_PADDING) == -1) {
    ERR_load_crypto_strings();
    ERR_error_string(ERR_get_error(), err);
    fprintf(stderr, "Error decrypting message: %s\n", err);
}

Thank you everyone for contributing to this post!!!