Sarah M., having split her seed backup into three pieces and hidden each in a clever location, confirmed on Thursday that she could presently remember exactly one of them.

The scheme itself was sound: no single piece reveals anything on its own, so each could be hidden boldly and separately. The flaw was entirely human — she hid them so well, and so long ago, that two now exist in a state best described as theoretical.

"One's in the safe. The other two are… safe," she said, gesturing vaguely at the general concept of her home. A simple record of where each piece lived would have spared her the afternoon.

A backup split for safety is only safe if you can still find the pieces.