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I have come across a file eraser called Eraser, and I have two questions about it:

  1. Are file erasers sufficient for completely removing secure files/folders on a computer (meaning is it possible, in any way, for the data to be recovered).
  2. (Slightly less important.) How can I verify the security of Eraser? Are there websites or companies that have checked the software for back-doors/security flaws that would compromise the security of my data?
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There are different aspects in your question.

  1. is it possible to securely wipe disks?

The technologies now allow secure erasure on many media. On magnetic disks, the principle is to rewrite many times every sector with specific patterns which have been proven to make the previous information unrecoverable even by looking in the edges. On SSD media, many manufacturers now provide special commands that allow the internal logic of the drive to perform the erasure.

So unless on SSD that do not provide a secure erasure command, it is normally possible to securely wipe a disk

  1. How can erasure be controlled?

Unless you have an electronic laboratory at hand, you cannot. For magnetic disks, you should unmount the disk and analyse the surfaces to find where residual magnetic traces can be observed. For SSD you should get direct access to the memory banks. You can only trust experts that pretend to have processed those analysis... or choose not to trust them.

  1. How can I be sure that product X provides secure erasure ?

You cannot. It is really a matter of trust. If you can find good reputations sources that are consistant in saying that the product uses this well-known methods and/or has been tested by that (good reputation) laboratory, the level of trust can be increased

  1. Where can I find an official list of secure products?

I can sell you the only true one, but it is very expensive. Joking of course... Because you have no reason to trust me. The problem is that as an individual human being you have no way to control what is written here or there. It is just up to you with you mere intelligence to try to guess whether you can trust a site, post, or editor. If you think you can trust your government (or a government of a foreign country that you know the language), some provide lists of tools that are blessed to use by their own services.

As usual, defining trust levels is very hard...

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I've tried that tool, and it's fairly good and secure. I have also tried to recover data (using professional software) after using eraser and nothing. It's not good as Blancoo or BCWipe, but it is sufficient.

Non-free tools have also verification of wiping process. Also I'm not sure if eraser will consider removing HPA and DCO.

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  • Forgive me, but "I couldn't do it" isn't really a compelling argument unless you specialize in forensics.
    – MechMK1
    Dec 9 '20 at 20:24
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  • If you have an SSD overwriting several times is IMHO neither needed nor helpful. Even with many magnetic drives it would not be needed nor helpful.

  • For SSDs you may never know, since the drive logic may decide to relocate a broken sector, which means that anything beyond a bypassing of the controller will not give you security if the file was deleted

  • what is indeed needed is a single overwriting of the potential contents of the file. Here filling all available space is enough under normal circumstances (i typically use dd)

  • Erase claims to be GPL, so the source should be available for review if you like

  • Consider using encryption.

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