No one has ever recovered overwritten data, as far as anyone can tell. Go look it up. The technique was only a theoretical attack on ancient MFM/RLL hard drive encoding (Gutmann’s paper). Even 20 year old drives’ (post 2001, approx) magnetic encoding are so small there isn’t an ‘edge’ to read on the bits. A single pass of random data is sufficient to permanently destroy data, even against nation-state level actors. Certainly enough for personal data.
Most of the patterns in the Gutmann method were designed for older MFM/RLL encoded disks. Gutmann himself has noted that more modern drives no longer use these older encoding techniques, making parts of the method irrelevant. He said “In the time since this paper was published, some people have treated the 35-pass overwrite technique described in it more as a kind of voodoo incantation to banish evil spirits than the result of a technical analysis of drive encoding techniques”
NOW THAT BEING SAID there is no harm in doing a secure, 35-pass overwrite other than the time, energy and disk wear. If watching all the bit-patterns of a DoD-level wipe using DBAN on a magnetic disk tickles your fancy, or you think this is a CIA misinformation campaign to get people to do something insecure so they can steal your secrets, please just go ahead and do a 35-pass overwrite with alternating bit patterns followed by random data. I can tell you that I believe in my heart-of-hearts, that one pass is sufficient.
THIS IS THE HILL I DIE ON.
No one has ever recovered overwritten data, as far as anyone can tell. Go look it up. The technique was only a theoretical attack on ancient MFM/RLL hard drive encoding (Gutmann’s paper). Even 20 year old drives’ (post 2001, approx) magnetic encoding are so small there isn’t an ‘edge’ to read on the bits. A single pass of random data is sufficient to permanently destroy data, even against nation-state level actors. Certainly enough for personal data.
from https://en.wikipedia.org/wiki/Gutmann_method :
More reading material:
NOW THAT BEING SAID there is no harm in doing a secure, 35-pass overwrite other than the time, energy and disk wear. If watching all the bit-patterns of a DoD-level wipe using DBAN on a magnetic disk tickles your fancy, or you think this is a CIA misinformation campaign to get people to do something insecure so they can steal your secrets, please just go ahead and do a 35-pass overwrite with alternating bit patterns followed by random data. I can tell you that I believe in my heart-of-hearts, that one pass is sufficient.
This is exactly what a cia analyst whose tan literally comes from their monitors and is never let out of Langley’s 38th sub basement would say.
Guess we’re doing 40 passes. Just to be sure. ;)