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I was wondering what is the difference between the various wiping methodologies that DBAN offers

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Once you start the program, there are a few methods available for wiping the disk.

1.- DoD 5220.22-M : I know that with this there are 7 passes, but not if it writes random data, or zeros or uses some other approach.

2.- Short DoD 5220.22-M : I know that this there are 3 passes,but not if it writes random data, or zeros or uses some other approach.

3.- RCMP TSSIT OPS-II : No idea of how this one works

4.- Gutmann : I know that this one are 35 passes, white blank and random write.

5.- PRNG : No idea of how this one works

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  • The DoD ones use patterns and random numbers. PRNG just writes random data.
    – SEJPM
    Mar 17, 2016 at 11:56
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    It's essentially the difference between saying "abra-cadabra" and "open-sesame". All the various methods may have had some degree of validity 20 years ago when Peter Gutman wrote his paper about data recovery. But for many years now all the various algorithms essentially amount to different interpretations of mythos. Among people who've studied modern hard drive recovery, it's believed a single over write is sufficient.
    – Steve Sether
    Mar 17, 2016 at 13:59
  • For the purpose of wiping data off of a HDD manufactured in the last 15 years, functionally there is no (proven) difference. They just take different amounts of time to complete.
    – TTT
    Sep 13, 2016 at 17:21

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For modern hard drives, the main difference is how long it takes -- the quality of the wipe is effectively constant between them. A three-letter agency may be able to recover data from a zero-wiped drive, but if your opposition is a three-letter agency, you really should be looking into physical destruction instead.

  1. DoD 5220.22-M seven-pass: I haven't been able to find a description of this, but I suspect it's a variation of the three-pass wipe, only with three values and their inverses.

  2. DoD 5220.22-M three-pass: Overwrite the data with a value, then with the inverse of that value, then with a random value, verifying the write after each step. The first two wipes theoretically pull the magnetic field fully one direction, then fully the other, eliminating any residue of the original value. The problem with this is that the on-disk encoding is not simple binary data; the encodings of a value and its inverse may not themselves be inverses.

  3. RCMP TSSIT OPS-II: Overwrite the data with zeroes, ones, zeroes, ones, zeroes, ones, and random data, and verify the final write. The same basic idea as DoD 5220.22-M, but with only a single verification step.

  4. Gutmann 35-pass: This writes a series of patterns that would randomize the residual magnetic fields of all hard drive technologies in common use 25 years ago. It is totally useless on a modern hard drive, first, because low-level storage techniques have changed wildly since then, and second, because modern drives store data in such small areas that there's essentially no remnant magnetic field after even a single write.

  5. PRNG: This over-writes the contents of the disk with pseudo-random data. It's theoretically better than a zero-wipe, and is just as fast.

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They main difference is the number of times, the same data gets overwritten. Some shred algorithms just write zeros, some write random data.

You should take a look at: https://en.wikipedia.org/wiki/Data_remanence#Specific_methods

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    Some shred methods write specific sequences of patterns that are believed to be more effective at erasing data remnants. Whether these are actually more effective or not on modern hard drives are questionable.
    – Lie Ryan
    May 16, 2016 at 14:17

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