If you need advice paranoid, the above methods do not help — even hundredfold mashing of information can be circumvented by making a map of the magnetization of disk "poutana". It will cost a lot, but you know, enemies will do anything.
By the way, suddenly thought that SSD like such a deprived, on the one hand, and, on the other, the bed-blocks, there is transferred to the mode "read-only", i.e. some information will be impossible to erase — ever.
Yes, but the forum is paranoid in the end, all came to the following:
1. Perfectly valid sulfuric acid, is injected directly into the surface of the rotating disk.
2. Even the above method will not help if the information you have will be aggressive to inquire.