Hi,
I am trying to implement DH key exchage using openssl in the same program, so I
generate DH parameters once, and then transfer the p and g to another DH
object, here is my code-
#include <stdio.h>
#include <string.h>
#include <openssl/dh.h>
#include <openssl/engine.h>
#include <time.h>
void hexprint(unsigned char *printBuf, int len)
{
int i;
for(i = 0; i < len; i++)
{
printf("%x ", printBuf[i]);
}
printf("\n");
}
int main(int argc, char *argv[])
{
DH *dhPar=DH_new();
DH *dhPar2=DH_new();
time_t rt;
srand((unsigned) time(&rt));
unsigned char *dhSec1;
unsigned char *dhSec2;
printf("Generate parameter \n");
DH_generate_parameters_ex(dhPar, 1024, DH_GENERATOR_2, 0);
unsigned char *parmp=malloc(sizeof(unsigned char *) *
BN_num_bytes(dhPar->p));
unsigned char *parmg=malloc(sizeof(unsigned char *) *
BN_num_bytes(dhPar->g));
memset(parmp, 0, BN_num_bytes(dhPar->p));
memset(parmg, 0, BN_num_bytes(dhPar->g));
BN_bn2bin(dhPar->p,parmp);
BN_bn2bin(dhPar->g,parmg);
BN_bin2bn(parmp,strlen(parmp), dhPar2->p);
BN_bin2bn(parmg,strlen(parmg), dhPar2->g);
DH_generate_key(dhPar);
DH_generate_key(dhPar2);
printf("Generate shared key in both \n");
dhSec1 = OPENSSL_malloc(sizeof(unsigned char) * DH_size(dhPar));
dhSec2 = OPENSSL_malloc(sizeof(unsigned char) * DH_size(dhPar2));
memset(dhSec1, 0, DH_size(dhPar));
memset(dhSec2, 0, DH_size(dhPar2));
printf("Now computing key \n");
DH_compute_key(dhSec1, dhPar2->pub_key, dhPar);
DH_compute_key(dhSec2, dhPar->pub_key, dhPar2);
printf("Secret Key 1: \n");
hexprint(dhSec1, 32);
printf("Secret Key 2: \n");
hexprint(dhSec2, 32);
free(dhSec1);
free(dhSec2);
DH_free(dhPar);
DH_free(dhPar2);
}
It gives me segmentation fault at "DH_generate_key(dhPar2)", what am I doing
wrong here?
I compiled it with "gcc dh.c -lcrypto -lssl", also individually did with
"-lssl" and "-lcrypto", but all three compiled program gave the same result at
the same place.
Please help.
