Consider following 2 disk wipe procedures, using only vanilla Windows installation:

First do a quick-format to make the disk appear empty, then do one of these:

  1. Just do full format of the disk.

  2. Bitlocker-encrypt the entire drive (all space) using a strong key which is then thrown away, leaving disk unusable until formatted.

Both are operations which can be started quickly and then left running unattended, and then the drive yanked out when it's finished. And the concern is wiping the the data that was on the disk previously.

Is doing 2 more secure than doing just 1? Or to put it other way, who can recover the original contents after alternative 1, and who can recover them after alternative 2?

So, the key point of this question is: is there any advantage of writing single pass of "random" data (by encrypting) instead of writing a single pass of zeros (by full format).

Bonus question: Can you suggest other alternatives for Windows 7 or 8, assuming no extra software can be installed?

  • There is a command line program called "cipher" that is included with Windows for use with the Encrypting File System functionality. The /W option performs a wipe of unallocated space in a specified directory or drive when using NTFS partitions. Seems like it may work for your needs.
    – PwdRsch
    Jun 27 '14 at 18:53

If I were you, I'd encrypt the whole thing, because it's really hard to securely erase an SSD. I don't remember the specifics of WHY at the moment, but there's another question on here that talks a bit about it. Anyway, the basic point is: if you can, encrypt the data. Just deleting it isn't necessarily secure.

EDIT: Just FYI, I'm not saying that a reformatting will be sufficient for an HDD either. It's just that SSD's pose their own set of challenges.

  • Yeah, but the key point of this question is, is there any advantage of writing single pass of "random" data (by encrypting) instead of writing a single pass of zeros (by full format).
    – hyde
    Jun 27 '14 at 18:07
  • SSDs are hard to erase, because they have spare capacity and wear leveling. So there's more chance of some parts of old data becoming uneraseable even if writing the disk fully, than with HDDs (though I don't think HDDs are immune to this either, they too have spare sectors to replace detected bad sectors, I think).
    – hyde
    Jun 27 '14 at 18:12
  • @hyde Writing a single pass of anything isn't likely to be that much more or less secure than a single pass of anything else. (Except, of course, if one of those passes is just a full copy of the target data.) If you want the extra assurance that comes with a mulit-pass wipe, and can't install third-party software, I suggest downloading a bootable ISO that has the appropriate tools. Windows has built-in CD burning support you can use to make the disc.
    – Iszi
    Jun 27 '14 at 18:22
  • @Iszi Ooh, good point. I assumed he meant no other software could be used. Excellent catch.
    – KnightOfNi
    Jun 28 '14 at 23:06

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