> hash all your files, then write at most N+1 (unused) blocks, stopping after each to check if any of your files got harmed
That strategy adds O(n^2) reads on top of O(n) writes, though.
Even reads don't come for free on modern multi-level cell NAND (due to read disturb), and for just a thousand blocks, you'd end up reading the first block a million times.
That's to say nothing of the time this would take.
You're right, this is a non-starter. I should stop posting late at night. The owner of a suspect device just needs to bite the bullet and use a destructive method.
That strategy adds O(n^2) reads on top of O(n) writes, though.
Even reads don't come for free on modern multi-level cell NAND (due to read disturb), and for just a thousand blocks, you'd end up reading the first block a million times.
That's to say nothing of the time this would take.