Most data in computer systems is constantly copied about to achieve normal computing tasks. Such copies are often left behind in places where normal access is no longer possible, but abnormal means may still retrieve the data. This is a note to explore a disk (or SSD) architecture to store data on a disk so as to allow simple and complete total elimination of access to the deleted data—all this without excessive change to the normal concept of what a disk does. The plan also achieves disk encryption as well so that the storage medium proper sees only encrypted data.
A new layer is imposed between normal hardware which I do not propose to change, and a classic kernel, or Keykos, for that matter. Whether this layer is implemented by including it in the kernel, or in the disk system is a security-marketing tradeoff. SSD usually employes an invisible indirection level to data blocks in order to ameliorate the limitation on lifetime total writes to a particular area of the SSD. This logic might well be integrated with that to reduce total complexity and latency.
The basic new cost is encryption of all the data on the disk. Hardware to encrypt or decrypt is not excessively expensive. Key management is a logical but not a performance problem.
There is a table with an entry per disk block holding the only copy of the encryption key. Each disk write is done with a new key. This table is not on the disk but it must be as persistent and reliable as required for the data. Perhaps a hash of the data is included but that is only as an extra check on disk integrity. If integrity is all then a simple checksum will do. If this also provides authentication (protection against malicious replacement of data) then a secure hash is needed.