// metadata map if metadata is nil.
func (ssec) CreateMetadata(metadata map[string]string, sealedKey SealedKey) map[string]string {
	if sealedKey.Algorithm != SealAlgorithm {
		logger.CriticalIf(context.Background(), Errorf("The seal algorithm '%s' is invalid for SSE-C", sealedKey.Algorithm))
	}

	if metadata == nil {
		metadata = make(map[string]string, 3)
	}

func (key *ObjectKey) Unseal(extKey []byte, sealedKey SealedKey, domain, bucket, object string) error {
	var unsealConfig sio.Config
	switch sealedKey.Algorithm {
	default:
		return Errorf("The sealing algorithm '%s' is not supported", sealedKey.Algorithm)
	case SealAlgorithm:
		mac := hmac.New(sha256.New, extKey)
		mac.Write(sealedKey.IV[:])
		mac.Write([]byte(domain))
		mac.Write([]byte(SealAlgorithm))

			AssociatedData: kmsCtx,
		})
		if err != nil {
			return err
		}

		sealedKey := objectKey.Seal(newKey.Plaintext, crypto.GenerateIV(rand.Reader), crypto.S3KMS.String(), bucket, object)
		crypto.S3KMS.CreateMetadata(metadata, newKey.KeyID, newKey.Ciphertext, sealedKey, cryptoCtx)
		return nil
	case crypto.SSEC:
		sealedKey, err := crypto.SSEC.ParseMetadata(metadata)
		if err != nil {
			return err
		}

// from the metadata using the SSE-C client key.
func unsealObjectKey(clientKey []byte, metadata map[string]string, bucket, object string) (key ObjectKey, err error) {
	sealedKey, err := SSEC.ParseMetadata(metadata)
	if err != nil {
		return key, err
	}
	err = key.Unseal(clientKey, sealedKey, SSEC.String(), bucket, object)
	return key, err
}

// EncryptSinglePart encrypts an io.Reader which must be the
// body of a single-part PUT request.

		return output, metabytes, err
	}

	outbuf := bytes.NewBuffer(nil)
	objectKey := crypto.GenerateKey(key.Plaintext, rand.Reader)
	sealedKey := objectKey.Seal(key.Plaintext, crypto.GenerateIV(rand.Reader), crypto.S3.String(), bucket, "")
	crypto.S3.CreateMetadata(metadata, key.KeyID, key.Ciphertext, sealedKey)
	_, err = sio.Encrypt(outbuf, bytes.NewBuffer(input), sio.Config{Key: objectKey[:], MinVersion: sio.Version20})
	if err != nil {