4 ms·

For the better part of a decade there was a challenge put out on the internet and put to every recovery company on the planet for a very standard 80GB drive tha

For the better part of a decade there was a challenge put out on the internet and put to every recovery company on the planet for a very standard 80GB drive that contained a standard FAT32 filesystem and a few Megabytes worth of files to be recovered after it had been written with zeros from /dev/zero on linux using DD. The challenge offered $10k for recovery of the files. Once the process had been explained not a single commercial company in the entire world believed they could recover that file and no one took up the challenge and it finished up about a decade ago. People have been doing some really extreme things to clear out drives including 5+ passes and using true random sources but the fact is it is well beyond commercial means to recover data on a drive that is simply set to all zero just once. Maybe a state actor somewhere could read the edges of the data or the theoretic differences of zeroing and its state before that 0 was written but so far no one in the past 2 decades has shown it happen. If you are destroying a drive that is highly secret that another nation might want then sure be paranoid, but otherwise there is no reason for anyone to do anything but zero out a drive and that includes almost every single company. Most drives these days come with a secure wipe and that is the fastest way to clear them. Use that or just zeros, anything else is not making the (ex) data more secure its just taking longer. [1]https://tinyapps.org/docs/recovering_data_from_zero_filled_hard_drive.html https://tinyapps.org/docs/recovering_data_from_zero_filled_h... is a similar more recent experiment but not the one referenced since that one disappeared years ago.

upofadown 5y ago
The article is about randomizing a drive before using it for full disk encryption. That does in fact require a random pattern. The idea is to hide the structure of the data. >...but otherwise there is no reason for anyone to do anything but zero out a drive and that includes almost every single company. Overwriting doesn't work with SSDs. They leave copies of data laying around on the disk if you do that. That is even if you zero the whole disk as they have extra space in the form of overprovisioning. >Most drives these days come with a secure wipe and that is the fastest way to clear them. Tests have shown that a significant proportion of SSDs do this badly.
hnbear 5y ago
A lot of this is driven by regulatory, compliance or other outside factors. Working in finance, healthcare, and other secure industries you must demonstrate control of the environment, which includes processes to clear up data. Once a standard is common it’s easier to follow it and demonstrate that adherence to a regulator than it is to invent your own process and convince them it’s safe. Even in current world with SSDs that don’t follow the same mechanics as spinning disks, regulators expect a 9-pass DoD wipe because that’s what they’re used to. It’s easiest to just pass drives to a certified data destruction company who will provide a cert of evidence they did a DoD, NIST, etc certified wipe. Reality is seldom part of the process. Similar is the process for password resets. Regulars ask for 90 day resets and crazy complexity schemes when NIST actually just recommends relatively sane complexity, slightly longer passwords and no rotation.

upofadown 5y ago

The article is about randomizing a drive before using it for full disk encryption. That does in fact require a random pattern. The idea is to hide the structure of the data. >...but otherwise there is no reason for anyone to do anything but zero out a drive and that includes almost every single company. Overwriting doesn't work with SSDs. They leave copies of data laying around on the disk if you do that. That is even if you zero the whole disk as they have extra space in the form of overprovisioning. >Most drives these days come with a secure wipe and that is the fastest way to clear them. Tests have shown that a significant proportion of SSDs do this badly.

hnbear 5y ago

A lot of this is driven by regulatory, compliance or other outside factors. Working in finance, healthcare, and other secure industries you must demonstrate control of the environment, which includes processes to clear up data. Once a standard is common it’s easier to follow it and demonstrate that adherence to a regulator than it is to invent your own process and convince them it’s safe. Even in current world with SSDs that don’t follow the same mechanics as spinning disks, regulators expect a 9-pass DoD wipe because that’s what they’re used to. It’s easiest to just pass drives to a certified data destruction company who will provide a cert of evidence they did a DoD, NIST, etc certified wipe. Reality is seldom part of the process. Similar is the process for password resets. Regulars ask for 90 day resets and crazy complexity schemes when NIST actually just recommends relatively sane complexity, slightly longer passwords and no rotation.