g++ behaving strangely with libssl

I've been trying to use the RSA C library on a C++ application (since it seems like the proper way to do it, due to the lack of an "official" [read: OpenSSL] C++ implementation). The thing is, whenever I try to compile a testing code:

#include <iostream>
#include <openssl/rsa.h>
#include <openssl/engine.h>
#include <unistd.h>
using namespace std;

int main(int argc, char *argv[]) {
    RSA *myKeyPair = RSA_generate_key(2048, 65537, NULL, NULL);
    unsigned char *to;
    unsigned char *totwo;

    if (myKeyPair == NULL) {
        cout << "ERROR 1" << endl;
        return 0;
    }

    to = (unsigned char *) malloc(RSA_size(myKeyPair) - 11);

    if (RSA_private_encrypt(13, (const unsigned char *)"Hello World!", to, myKeyPair, RSA_PKCS1_PADDING) == -1) {
        cout << "ERROR 2" << endl;
        return 0;
    }

    cout << to << endl;

    totwo = (unsigned char *) malloc(RSA_size(myKeyPair) - 11);

    if (RSA_public_decrypt(13, to, totwo, myKeyPair, RSA_PKCS1_PADDING) == -1) {
        cout << "ERROR 3" << endl;
        return 0;
    }

    cout << totwo;

    free(to);
    free(totwo);
    RSA_free(myKeyPair);
    return 0;
}

I get undefined reference errors for all RSA_* functions (please notice that I AM linking with -lssl). To make it even weirder, compiling the very same code using GCC does the job (well, of course, it won't compile because of the C++ std lib references, but the point is that I don't get undefined reference for RSA functions).

Any ideas on how to go about this? (without recurring to any other lib?).