I recently watched a talk from 27C3 [1] about data recovery by the CEO of just such a data recovery firm [2]. (Very interesting with a rough outline of what the

I recently watched a talk from 27C3 [1] about data recovery by the CEO of just such a data recovery firm [2]. (Very interesting with a rough outline of what they do and many cool anecdotes from the field.) He more or less said that recovering all the data from a hard drive that cannot be read with its read/write head (either the original or a spare) would not be feasible or economical for his company. He said it would take several years. (And that’s without even considering overwritten data.) When asked what’s the best way to destroy data forever he said that overwriting the data once is sufficient in any case. I take from this that at least his company and presumably other data recovery companies cannot read data that was overwritten once, even in principle (i.e. it’s not just a question of throwing enough resources at it). I have my doubts that the government has capabilities beyond that. [1] Link to mp4 (h.264): http://mirror.fem-net.de/CCC/27C3/mp4-h264-HQ/27c3-4231-en-datenrettung_fun_with_hard_drives.mp4 http://mirror.fem-net.de/CCC/27C3/mp4-h264-HQ/27c3-4231-en-d...; link to slides: http://events.ccc.de/congress/2010/Fahrplan/events/4231.en.html http://events.ccc.de/congress/2010/Fahrplan/events/4231.en.h... [2] http://www.attingo.com/en/ http://www.attingo.com/en/