Add "random overwrite" option in "Tools - Drive Wiper - Security" selection.

[SG H]

Good day, sir.

I can't sure this may effect for more securely erase free space on a drive.

But, in my thoughts, if each sector's overwrite passes is random(1 or 3 or 7 or 35), the contents on drive's free space might be never recovered because sectors in one file has been erased by random pattern of overwrite passes.

Of course, this option must be disabled on SSD Drive.

Can I count on this feature?

[nukecad]

1 pass overwrite is sufficent.

Have a read of this : https://www.howtogeek.com/115573/htg-explains-why-you-only-have-to-wipe-a-disk-once-to-erase-it/

[Augeas]

It is effectively random, as the existing data has been randomised before writing, and the overwriting pattern of zeroes is also randomised, so there is no concept of overwriting a one with a zero etc as many think (at least not in the last 30 years).

[SG H]

@nukecad

I really thank you for show me that article.

I read it all.

Before read it, I just believe I have to use higher passes for wipe drive. But I was wrong.

Thanks you for fix my wrong knowledge in my mind.

 

@Augeas

Yes, it right. I had stupid idea.

[jimmyxx]

Well you're not wrong. The admins have just assumed ccleaners algorithm. Neither has any idea what ccleaner writes to any byte and i mean that in the nicest way. How does howtogeek have any idea what ccleaner does? there is not a standard of bytes written. All that paper focuses on is a 1996 document anyone with any brains knows from 1996. 
 

nuke mentioned one pass and linked an outdated pointless article but never once mentioned anything to do with one pass which he/she pointed out.

[Augeas]

You don't give up, do you? It must be the tolerant attitude we have here.

[SG H]

Oh... Sorry for the delay in getting back here.

Actually, that idea is one just crossed my mind with thought that is there any chance to reduce some overwrite passes though HDD wipe must have done by a lots of overwrite pass.

Also I didn't think how it could be verified as expected. So, I said.

On 30/10/2019 at 05:43, SG H said:

I can't sure this may effect for more securely erase free space on a drive.

 

After I see new reply, I looked for "secure deletion" and found paper which introduce "The Gutmann method".

https://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html

"Epilogue" in this paper say "For any modern PRML/EPRML drive, a few passes of random scrubbing is the best you can do.". He made "The Gutmann method" and said that.

Also I got another paper in 2008.

https://www.vidarholen.net/~vidar/overwriting_hard_drive_data.pdf

This paper show the probability of recoverability one bit (not one byte) using MFM.

After read this, though process in this paper may be wrong, I do not really think there are any chance to recover data securely erased using one pass with random data.

If you want wipe data truly, you may crack your HDD by hammer, too.

I'm stick to one pass overwrite now.

Thank you for reply. I don't feel like I need to count on what I said.

P.S. You may rename file as "153"(any random digits and make no extension) before normal/secure erase private data(software key, backup code or so on) to make sure no clue via filename in MFT.

Move each file to root dirctory in drive may good, too.

[nukecad]

1 hour ago, SG H said:

If you want wipe data truly, you may crack your HDD by hammer

Usually works.

Use a big one and smash it to little pieces to make sure.

[Andavari]

5 hours ago, SG H said:

Also I didn't think how it could be verified as expected.

As for verifying data has been successfully overwritten you can use Recuva to scan the drive(s) after the wipe.

[SG H]

Yes, I know Recuva and one pass is enough because I saw no file could be recovered via Recuva.

But, currently, because there are no option for "random passes" overwrite, I can't test it.

Also, I supposed to focus on physical recover level not software level :)