| FWIW: This seems to mostly be lore.
See http://www.nber.org/sys-admin/overwritten-data-guttman.html Note also "Since writing the above, I have noticed a comment attributed to Gutmann conceding that overwritten sectors on "modern" (post 2003?) drives can not be read by the techniques outlined in the 1996 paper, but he does not withdraw the overwrought claims of the paper with respect to older drives." (the comment is at http://seclists.org/bugtraq/2005/Jul/464) As for SSD's, it's harder to say because of wear leveling and bad sector replacement. They internally have their own translation layers, and so the overwritten data may not end up where the original data was (this is itself a complicated topic. http://codecapsule.com/2014/02/12/coding-for-ssds-part-3-pag... is a reasonble intro) However, one neat thing about them is that there are plenty of SSD's that do hardware encryption by default. When they get init'd, they set the key. You can reset the key, and then, pretty much, assuming the SSD's have not been backdoored by our security agencies, it doesn't matter what you do ;) This assumes you just want to destroy all the data though, not just some of it. |