// domain (SSE-C or SSE-S3).
func (key ObjectKey) Seal(extKey []byte, iv [32]byte, domain, bucket, object string) SealedKey {
	if len(extKey) != 32 {
		logger.CriticalIf(context.Background(), errors.New("crypto: invalid key length"))
	}
	var (
		sealingKey   [32]byte
		encryptedKey bytes.Buffer
	)
	mac := hmac.New(sha256.New, extKey)
	mac.Write(iv[:])
	mac.Write([]byte(domain))
	mac.Write([]byte(SealAlgorithm))

	if err != nil {
		return nil, err
	}
	extKey, err := GlobalKMS.Decrypt(context.TODO(), &kms.DecryptRequest{
		Name:           keyID,
		Ciphertext:     kmsKey,
		AssociatedData: kmsContext,
	})
	if err != nil {
		return nil, err
	}
	var objectKey crypto.ObjectKey
	if err = objectKey.Unseal(extKey, sealedKey, crypto.S3.String(), bucket, ""); err != nil {
		return nil, err
	}