The present invention discloses methods for protecting data integrity of updatable data against unauthorized modification. A method for protecting data integrity of updatable data in a storage system, the method including the steps of: storing a data copy of the data in the storage system; upon storing the data copy, transforming the data copy into at least one transformed copy of the data; storing at least one transformed copy in the storage system; upon a request to read the data, reading the data copy and at least one transformed copy; transform-comparing the data copy and at least one transformed copy; and designating the data integrity of the data as verified contingent upon the data copy and at least one transformed copy being identical.