if !etag.IsEncrypted() {
		return etag, nil
	}
	mac := hmac.New(sha256.New, key)
	mac.Write([]byte(HMACContext))
	decryptionKey := mac.Sum(nil)

	plaintext := make([]byte, 0, 16)
	etag, err := sio.DecryptBuffer(plaintext, etag, sio.Config{
		Key: decryptionKey,
	})
	if err != nil {
		return nil, err
	}
	return etag, nil
}

// Parse parses s as an S3 ETag, returning the result.

		}
		key, err := decryptObjectMeta(key, o.Bucket, o.Name, o.UserDefined)
		if err != nil {
			return nil, err
		}
		mac := hmac.New(sha256.New, key)
		mac.Write([]byte(baseKey))
		return sio.DecryptBuffer(nil, input, sio.Config{Key: mac.Sum(nil)})
	}
}

// decryptPartsChecksums will attempt to decrypt and decode part checksums, and save
// only the decrypted part checksum values on ObjectInfo directly.