The disclosure provides a method for ensuring that data stored on rewritable storage is immutable. The method includes initializing selected user-addressable blocks of storage to a writable state. In addition, the method includes accepting data to be stored in specified user-addressable blocks. Also, the method includes determining if the specified block(s) is writable. Also, the method includes storing the accepted data to the rewritable storage. Moreover, the method includes setting the state of the specified block(s) to non-writable. Each user-addressable block of storage is mapped to at least one block of rewritable storage and initializing selected user-addressable blocks of storage to a writable state includes storing predetermined bit patterns into the corresponding blocks of rewritable storage such that for each selected user-addressable block of storage, the contents of the corresponding blocks of rewritable storage satisfy a predetermined mathematical relationship.