-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

#include <stdio.h>
#include <openssl/ssl.h>

int main()
{
    int l;

    // init SSL stuff
    SSL_library_init();
    SSL_load_error_strings();
    SSL_METHOD *meth=SSLv3_method();
    SSL_CTX *ctx=SSL_CTX_new(meth);
    SSL *ssl=SSL_new(ctx);

    // load pem file
    SSL_use_RSAPrivateKey_file(ssl, "./mykey.pem", SSL_FILETYPE_PEM);

    // get my heap reference of private key struct
    EVP_PKEY *pkey = SSL_get_privatekey(ssl);

    // get my heap reference of RSA private key struct
    RSA *rsa = EVP_PKEY_get1_RSA(pkey);

    // get the length
    l = i2d_RSAPrivateKey(rsa, NULL);

    printf("Found key sized %d bytesn", l);

    // make room enough to contain the key
    unsigned char *b = malloc(l);
    i2d_RSAPrivateKey(rsa, &b);

    printf("RSA key: %sn", base64encode(b, l));

    return 0;
}