我需要一些帮助算法Diffie Hellman在openssl我有素数（p），生成器（g），用户A的私钥和用户B的公钥。我需要计算共享密钥。我写了这段代码，但代码一直执行到这一行

 int dhSize = DH_size(dh->priv_key);

这是完整的代码：

#include <stdio.h>
#include <openssl/dh.h>

const char* userA_PrivateKey = "90ff0";
const char* userB_PublicKey = "9d1a59";
const char* p = "66c2fa";
const char* g = "2";

int main(void)
{
    DH *dh = DH_new();

    BN_dec2bn(&dh->g, g);
    BN_hex2bn(&dh->p, p);
    BN_hex2bn(&dh->priv_key, userA_PrivateKey);

    BIGNUM *pubKeyUserB = NULL;
    BN_dec2bn(&pubKeyUserB, userB_PublicKey);

    //Compute the shared secret
    int secret_size;
    unsigned char *secret;
    printf(" Compute DH_size \n");
    int dhSize = DH_size(dh->priv_key);
    printf(" dhSize = %d \n"); //NOT EXECUTED 
    secret = OPENSSL_malloc(sizeof(unsigned char) * dhSize);

    if(0 > (secret_size = DH_compute_key(secret, pubKeyUserB, dh->priv_key)))
    {
        printf("error \n");
    }

    return 0;
}

我有两个问题：

1）printf，打印dhSize根本不执行

2）我不确定我是否正确设置了值g， p，priv键？函数DH_compute_key会使用我的g和p吗？