ECDH

[Fábio Resner]

Hi,

I'm trying to write an app to generate public/private/shared key for ECDH.
Here is what I was able to build based on examples:

#include <openssl/ssl.h>

#define ECDH_SIZE 67

int main() {
EC_KEY *ecdh = EC_KEY_new();
const EC_POINT *point = NULL;

EC_POINT *point2;
const EC_GROUP *group;

// const void *pubkey = NULL;
unsigned char *pubkey = NULL;
void *shared = NULL;

//Generate Public
ecdh = EC_KEY_new_by_curve_name(NID_secp521r1);
EC_KEY_generate_key(ecdh);

point = EC_KEY_get0_public_key(ecdh);
EC_POINT_point2oct(EC_KEY_get0_group(ecdh), point,
POINT_CONVERSION_COMPRESSED, pubkey, ECDH_SIZE, NULL);

//ComputeKey
group = EC_KEY_get0_group((ecdh));
point2 = EC_POINT_new(group);

EC_POINT_oct2point(group, point2, pubkey, ECDH_SIZE, NULL);

ECDH_compute_key(shared, ECDH_SIZE, point2, ecdh, NULL);
EC_POINT_free(point2);
EC_KEY_free(ecdh);
ecdh = NULL;

printf("To the end");

return 0;
}

But it just broke on EC_POINT_oct2point(group, point2, pubkey, ECDH_SIZE,
NULL);
And pubkey is exiting EC_POINT_point2oct(EC_KEY_get0_group(ecdh), point,
POINT_CONVERSION_COMPRESSED, pubkey, ECDH_SIZE, NULL); with a NULL value.
The program exists and gives no segFAULT or any erros messages.

Any suggestions?

Thanks,

-- 
Fabio Resner.