Use OpenSSL in C++Builder

Question

I'm compiling an app in C++Builder 10 Seattle, and trying to use OpenSSL for RSA work.

I followed this tutorial:

How to Use OpenSSL to Generate RSA Keys in C/C++

Here is the code:

#include <stdio.h>
#include <openssl/rsa.h>
#include <openssl/pem.h>

bool generate_key()
{
    int             ret = 0;
    RSA             *r = NULL;
    BIGNUM          *bne = NULL;
    BIO             *bp_public = NULL, *bp_private = NULL;

    int             bits = 2048;
    unsigned long   e = RSA_F4;

    // 1. generate rsa key
    bne = BN_new();
    ret = BN_set_word(bne,e);
    if(ret != 1){
        goto free_all;
    }

    r = RSA_new();
    ret = RSA_generate_key_ex(r, bits, bne, NULL);
    if(ret != 1){
        goto free_all;
    }

    // 2. save public key
    bp_public = BIO_new_file("public.pem", "w+");
    ret = PEM_write_bio_RSAPublicKey(bp_public, r);
    if(ret != 1){
        goto free_all;
    }

    // 3. save private key
    bp_private = BIO_new_file("private.pem", "w+");
    ret = PEM_write_bio_RSAPrivateKey(bp_private, r, NULL, NULL, 0, NULL, NULL);

    // 4. free
    free_all:

    BIO_free_all(bp_public);
    BIO_free_all(bp_private);
    RSA_free(r);
    BN_free(bne);

    return (ret == 1);
}

int main(int argc, char* argv[]) 
{
    generate_key();
    return 0;
}

When I added libeay32.lib and ssleay32.lib to my project, I got an error message:

[ilink32 Error] Error: 'C:\USERS\ERICWANG\DESKTOP\TESTOPENSSL2\LIB\LIBEAY32.LIB' contains invalid OMF record, type 0x21 (possibly COFF)

I've seen some tips like using coff2omf and implib tools, but both didn't work.

1. I used coff2omf.exe to convert libeay32.lib. I put coff2omf.exe and libeay32.lib in the same folder, and entered this command:

   coff2omf libeay32.lib Blibeay32.lib
   

   It said:

   ERROR: COFF error: libeay32.lib : invalid machine type detected

2. I tried to convert libeay32.lib to a .dll file using implib.exe. I entered this command:

   implib libeay32.lib Blibeay32.dll
   

   It said:

   Error : unable to open file

   And my libeay32.lib change its size to 1KB file. Which means the file was wrong.

Answer 1

OpenSSL works just fine in C++Builder. I use it in my own C++Builder apps.

You cannot use the .lib files that are included with the pre-compiled OpenSSL DLLs. Those .lib files are meant for Visual Studio.

In C++Builder, you need to use C++Builder's implib or mkexp command-line utility to create C++Builder-compatible import libs from the DLLs. Use implib for 32bit DLLs and mkexp for 64bit DLLs.

It works fine, I have been using this technique for years when new OpenSSL versions are released.

Your implib command is wrong. You cannot "convert libeay32.lib to a .dll file". The first parameter is an output parameter, the second parameter is an input parameter. You need to create a .lib file for an existing DLL. There is no Blibeay32.dll file, which is why you are getting the "unable to open file" error. Drop the B and use the correct DLL filenames:

implib libeay32.lib libeay32.dll
implib ssleay32.lib ssleay32.dll

mkexp libeay32.a libeay32.dll
mkexp ssleay32.a ssleay32.dll

This will create .lib or .a files containing references for importing the functions from libeay32.dll and ssleay32.dll, respectively.