Schneier 7 Pass


New Member
I apologise if this topic has been dealt with before, if it has I cannot find it!

Just wanted to know what the Schneier 7 pass system was. I did assume it was something to do with the encryption and security expert Bruce Schneier but he says it is not.

Does anyone know what the system is and has it any advantages over the DOD 7 pass

Many thanks
Bruce Schneier in his book "Applied Cryptography" (1996): said:
Most commercial programs that claim to implement the DoD standard overwrite three times: first with all ones, then with all zeros, and finally with a repeating one-zero pattern. Given my general level of paranoia, I recommend overwriting a deleted file seven times: the first time with all ones, the second time with all zeros, and five times with a cryptographically secure pseudo-random sequence." (Schneier B, 1996)

But he then goes on to say…

Recent developments at the National Institute of Standards and Technology with electron-tunnelling microscopes suggest even that might not be enough. Honestly, if your data is sufficiently valuable, assume that it is impossible to erase data completely off magnetic media. Burn or shred the media; it's cheaper to buy media new than to lose your secrets." (Schneier B, 1996).