init_pubkey_from_privkey
ATTRIBUTE_WARN_UNUSED_RET int init_pubkey_from_privkey(ec_pub_key *pub_key, ec_priv_key *priv_key);
ret = init_pubkey_from_privkey(&(kp->pub_key), &(kp->priv_key));
ret = init_pubkey_from_privkey(&(kp->pub_key), &(kp->priv_key));