7 ms·

That sounds interesting, how do you do that?

m3kw9 6y ago
It was a joke
steelframe 6y ago
Per-volume zero-based one-time pad (PVZBOTP). It's a common technique used by almost all Fortune 500 organizations these days. The tl;dr is that you generate an encrypted volume that, when XOR'd with a volume consisting entirely of zeroes, produces the original plaintext volume.
- hailwren 6y ago
  I laughed.
- dpc_pw 6y ago
  probably the best joke in HN today :)
xwdv 6y ago
The key is to encrypt the entire drive, then lightly overwrite all ones in the volume with zeros in one pass, such that with some forensic tools you can deduce if the original bit was previously 1. When you want to access the data, you set those bits back to one, then decrypt the drive with the original encryption algorithm. The first two bits (or any two bits you want really, it’s just convention to use the first two) on the volume must always be 0 and 1. First write both bits to 0 hard multiple times, then write the second bit to 1 and lightly write it to zero. These two bits will serve as a control for the forensic tool to determine the difference between a hard zero and a soft zero, and thus figure out the rest of your volume. If an unknowing person simply looks at the drive by regular software means, the computer will simply show a drive of all zeros.
- Thorrez 6y ago
  Is there any evidence that that actually works? Or are you joking too?
  - xwdv 6y ago
    Oh it works, there’s definitely ways to retrieve past writes from a hard drive. You think just zero writing it out once is enough? Why do you think DoD standards call for no less than 3 writes when erasing a drive? Be careful.
    - Thorrez 6y ago
      >there’s definitely ways to retrieve past writes from a hard drive. Please provide some evidence. > You think just zero writing it out once is enough? I definitely think a single zero write on a disk drive is enough (or at least that it's as good as 3 writes or 100 writes). There's no evidence anyone has ever recovered a file that was overwritten by zeros a single time on any hard disk drive from the last 20 years. https://en.wikipedia.org/wiki/Data_remanence#Feasibility_of_recovering_overwritten_data https://en.wikipedia.org/wiki/Data_remanence#Feasibility_of_... https://news.ycombinator.com/item?id=511568 https://news.ycombinator.com/item?id=511568 Hmm, it looks like the site is down now. Well, here's a copy of the content: https://www.techpowerup.com/forums/threads/the-great-zero-challenge.79982/ https://www.techpowerup.com/forums/threads/the-great-zero-ch... I might have to run my own Great Zero Challenge v2. > Why do you think DoD standards call for no less than 3 writes when erasing a drive? I think you're referring to an old DoD standard. Prior to 2007 the DoD recommended that. Now they don't recommend that, and only recommend degaussing or destruction of the drive. https://en.wikipedia.org/wiki/Data_remanence#Standards https://en.wikipedia.org/wiki/Data_remanence#Standards Old one: https://it.ouhsc.edu/policies/documents/infosecurity/DoD_5220.pdf https://it.ouhsc.edu/policies/documents/infosecurity/DoD_522... New one: https://files.meetup.com/7887332/107-009-005_Exhibit_B.pdf https://files.meetup.com/7887332/107-009-005_Exhibit_B.pdf

It was a joke

Per-volume zero-based one-time pad (PVZBOTP). It's a common technique used by almost all Fortune 500 organizations these days. The tl;dr is that you generate an encrypted volume that, when XOR'd with a volume consisting entirely of zeroes, produces the original plaintext volume.

hailwren 6y ago
I laughed.
dpc_pw 6y ago
probably the best joke in HN today :)

xwdv 6y ago

The key is to encrypt the entire drive, then lightly overwrite all ones in the volume with zeros in one pass, such that with some forensic tools you can deduce if the original bit was previously 1. When you want to access the data, you set those bits back to one, then decrypt the drive with the original encryption algorithm. The first two bits (or any two bits you want really, it’s just convention to use the first two) on the volume must always be 0 and 1. First write both bits to 0 hard multiple times, then write the second bit to 1 and lightly write it to zero. These two bits will serve as a control for the forensic tool to determine the difference between a hard zero and a soft zero, and thus figure out the rest of your volume. If an unknowing person simply looks at the drive by regular software means, the computer will simply show a drive of all zeros.

Thorrez 6y ago
Is there any evidence that that actually works? Or are you joking too?
- xwdv 6y ago
  Oh it works, there’s definitely ways to retrieve past writes from a hard drive. You think just zero writing it out once is enough? Why do you think DoD standards call for no less than 3 writes when erasing a drive? Be careful.
  - Thorrez 6y ago
    >there’s definitely ways to retrieve past writes from a hard drive. Please provide some evidence. > You think just zero writing it out once is enough? I definitely think a single zero write on a disk drive is enough (or at least that it's as good as 3 writes or 100 writes). There's no evidence anyone has ever recovered a file that was overwritten by zeros a single time on any hard disk drive from the last 20 years. https://en.wikipedia.org/wiki/Data_remanence#Feasibility_of_recovering_overwritten_data https://en.wikipedia.org/wiki/Data_remanence#Feasibility_of_... https://news.ycombinator.com/item?id=511568 https://news.ycombinator.com/item?id=511568 Hmm, it looks like the site is down now. Well, here's a copy of the content: https://www.techpowerup.com/forums/threads/the-great-zero-challenge.79982/ https://www.techpowerup.com/forums/threads/the-great-zero-ch... I might have to run my own Great Zero Challenge v2. > Why do you think DoD standards call for no less than 3 writes when erasing a drive? I think you're referring to an old DoD standard. Prior to 2007 the DoD recommended that. Now they don't recommend that, and only recommend degaussing or destruction of the drive. https://en.wikipedia.org/wiki/Data_remanence#Standards https://en.wikipedia.org/wiki/Data_remanence#Standards Old one: https://it.ouhsc.edu/policies/documents/infosecurity/DoD_5220.pdf https://it.ouhsc.edu/policies/documents/infosecurity/DoD_522... New one: https://files.meetup.com/7887332/107-009-005_Exhibit_B.pdf https://files.meetup.com/7887332/107-009-005_Exhibit_B.pdf