logger.CriticalIf(context.Background(), errors.New("Unable to encrypt io.Reader using object key"))
	}
	return r
}

// EncryptMultiPart encrypts an io.Reader which must be the body of
// multi-part PUT request. It derives an unique encryption key from
// the partID and the object key.
func EncryptMultiPart(r io.Reader, partID int, key ObjectKey) io.Reader {
	partKey := key.DerivePartKey(uint32(partID))