PARAM_BUF_SZ
uint8_t pubbuf[PARAM_BUF_SZ]; /* expressly bigger than max key size * 3 */
uint8_t prvbuf[PARAM_BUF_SZ]; /* expressly bigger than max key size * 3 */
uint8_t sdbuf[PARAM_BUF_SZ]; /* expressly bigger than max key size * 3 */
RAND_bytes(pubbuf, PARAM_BUF_SZ);
RAND_bytes(prvbuf, PARAM_BUF_SZ);
RAND_bytes(sdbuf, PARAM_BUF_SZ);