ok := bd != nil && C._goboringcrypto_EC_KEY_set_private_key(key, bd) != 0
	if bd != nil {
		C._goboringcrypto_BN_free(bd)
	}
	if !ok {
		C._goboringcrypto_EC_KEY_free(key)
		return nil, fail("EC_KEY_set_private_key")
	}
	k := &PrivateKeyECDSA{key}
	// Note: Because of the finalizer, any time k.key is passed to cgo,
	// that call must be followed by a call to runtime.KeepAlive(k),

	ok := b != nil && C._goboringcrypto_EC_KEY_set_private_key(key, b) != 0
	if b != nil {
		C._goboringcrypto_BN_free(b)
	}
	if !ok {
		C._goboringcrypto_EC_KEY_free(key)
		return nil, fail("EC_KEY_set_private_key")
	}
	k := &PrivateKeyECDH{curve, key}
	// Note: Same as in NewPublicKeyECDH regarding finalizer and KeepAlive.
	runtime.SetFinalizer(k, (*PrivateKeyECDH).finalize)
	return k, nil
}