2017/12/03 9:57 "Colin Watson" <<a href="mailto:cjwatson@ubuntu.com">cjwatson@ubuntu.com</a>>: > > On Sun, Dec 03, 2017 at 08:49:22AM +0900, Joel Rees wrote: > > If you are doing things that your local version of the NSA has interest in > > (or your local organized crime guys), for the cost of a scanning electron > > microscope and a bit of time, all sorts of things are recoverable. > > Do you have a citation for a case where this has in fact been done after > a single straightforward pass of overwriting with (e.g.) zeroes? This > idea has been wandering around for a long time, but it often seems to > resist substantiation. > > <a href="https://www.nber.org/sys-admin/overwritten-data-gutmann.html">https://www.nber.org/sys-admin/overwritten-data-gutmann.html</a> and > <a href="http://www.infosecisland.com/blogview/16130-The-Urban-Legend-of-Multipass-Hard-Disk-Overwrite.html">http://www.infosecisland.com/blogview/16130-The-Urban-Legend-of-Multipass-Hard-Disk-Overwrite.html</a> > (aside from the annoying popup in the latter case) look like plausible > rebuttals. People love to claim inconvenient information has been debunked and relegated to urban myth. But there are companies that advertise such services. A really quick search of Google produces these kinds of links, as well as the "debunking" kind: <a href="https://news.ycombinator.com/item?id=511568">https://news.ycombinator.com/item?id=511568</a> <a href="https://digital-forensics.sans.org/blog/2009/01/28/spin-stand-microscopy-of-hard-disk-data">https://digital-forensics.sans.org/blog/2009/01/28/spin-stand-microscopy-of-hard-disk-data</a> The problem I have with the debunking is that they use absence of evidence as if it is evidence. There may be some validity to the idea that current drive densities make things infeasible *now*. Now is not much comfort tomorrow, if you have that kind of data. But most of us don't, really. But there are several layers in the stack at which our attempts to erase data can be foiled, and we should understand that. This thread has left out a couple, BTW.