Data Remanence, n.
The residual representation of data that remains even after attempts have been made to remove or erase the data.
It’s a well-known fact that simply deleting a file on your computer doesn’t actually delete the data that was in it from your hard disk; in fact it’s rather trivial to use software that can automatically discover and reconstruct often a surprising amount of data you’d long ago deleted. To really remove that data from a disk (e.g. to safely discard, sell, or otherwise give it away), you have to go a step further and wipe it away.
It’s only a slightly lesser known fact that to properly wipe a file from your hard drive, you have to use software that overwrites it numerous times; popular methods today include the Schneier 7-Pass, NIST, DoD, and, perhaps most famously, the Gutmann 35-Pass Method, with most modern software implementing at least a few of these different methods.
But with multiple passes comes increased time, and with increased time comes a decrease in people’s willingness to do it. So it’s worth exploring a critical question, namely: Is it really worth it?
The answer is, perhaps surprisingly, “No.” Continue reading
