int ECDH_compute_key(unsigned char *key, const EC_POINT *pub_key, EC_KEY *eckey)
int ECDH_compute_key(void *out, size_t outlen, const EC_POINT *pub_key, EC_KEY *eckey, void *(*KDF)(void *in, size_t inlen, void *out, size_t outlen))
int ECDH_compute_key(unsigned char *key, const EC_POINT *pub_key, EC_KEY *eckey){	ECDH_DATA *ecdh = ecdh_check(eckey);	if (ecdh == NULL)		return 0;	return ecdh->meth->compute_key(key, pub_key, eckey);}