DH_compute_key
ret = DH_compute_key(key, ctx->peerkey->pkey.dh->pub_key,
int DH_compute_key(unsigned char *key,const BIGNUM *pub_key,DH *dh);
if ((key_len = DH_compute_key(key, DH_get0_pub_key(dh_peer), dh)) <= 0)
if ((kout = DH_compute_key(kbuf, dh_pub, kex->dh)) < 0 ||