On Tue, Dec 30, 2025 at 01:13:39PM -0600, Robert B. Carleton wrote: > Would overwriting the a partition be sufficient to make the data in the d > partition unusable?
For most purposes, in simple and practical terms, yes. A few points to note: Technically the actual encryption keys used are derived from both the keydisk and some metadata at the start of the 'd' partition. But destroying either one of those makes recovery mathematically implausible, (with current common knowledge and technology). Of course, if this is a multi-user system then you need to consider that anybody with root access can dump a copy of the key data for later use, but from your original mail it seems that that is an accepted risk in your case. Theoretically, the key data might remain on the media after you overwrite the 'a' partition, in blocks that have been re-mapped as bad by the drive firmware. The chances of anybody randomly finding your drive, and having the ability to recover that data, and then decrypt the rest of the drive seems somewhat unlikely.
