Any material I've come up with for data destruction standards relate to completely wiping (ATA Secure Erase) and physically destroying hard drives, but I haven't been able to find much about standards for destroying individual files. Are there such standards, and if so how can they be properly followed?
1) With modern filesystems, there is no more concept of securely deleting an individual file. It might have been copied around, snapshotted, written to a different location upon editing, etc.
2) With modern drives, there is no deletion / wipe without confirming it. Some drives have had a Secure Wipe command flat-out lies to you, returning immediately while doing nothing.
- See SSD (Flash Memory) security when data is encrypted in place
- Use Full Disk Encryption.
- Pretty much forget about the concept of securely deleting a file and knowing it is really gone. Even with a freespace wipe, you've still got cache files, preloads, snapshots, slack space (though some utilities wipe that)...