Generating RSA Key Pair Programmatically using OpenSSL

#include "stdafx.h"
#include <conio.h>
#include <openssl/rsa.h>
#include <openssl/bio.h>
#include <openssl/x509.h>
#include <stdlib.h>
#include <stdio.h>
 

int _tmain(int argc, _TCHAR* argv[])
{
    RSA *myrsa;
    unsigned long e = RSA_3;
    BIO* out = NULL
    FILE* fp;
    myrsa = RSA_generate_key(2048,e,NULL,NULL);

    out=BIO_new(BIO_s_file());
    

    if(myrsa==NULL){
        printf("error in generating keypair..");
        printf("press any key to exit..");
        _getch();
    }
    
    fp=fopen("rsakeypair.txt","wb");
    out = BIO_new_fp(fp,BIO_CLOSE);
    BIO_printf(out,"\n");
    RSA_print(out,myrsa,0);
    fclose(fp); _getch(); return(0);
}

The above example program generates a 2048 bit RSA Key pair. It also generates the p,q,n,e and d sections into the text file. In order to build this sample using Visual C++, you will need to build OpenSSL first. After you build OpenSSL, you can then include the generated headers to your VC/Include folder. You will also need to include the the lib files generated by OpenSSL onto VC/Lib. The above example program is written in VS05. OpenSSL simply rocks!

Code + Demo + ReadmeFile : Here