Why 35 passes is needed

Computer Help and Discussions The Lounge
1

Some claim that 35 passes is overkill. Some claim that only 1 pass can render an HDD with files that are unrecoverable. Is this really true? I want to know, because I found the following while searching the web for different data recovery solutions:

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Data Recovery Standards:

Simple Overwrite, 1 pass. D.o.D 5220, 3 passes. N.S.A., 7 passes. Gutmann, 35 passes.

In reply to "Can overwritten data be recovered?" Yes.

As data is written to tracks and recovery programs aim at those tracks which are overwritten, the best data recovery teams sense what data is between the tracks. The name of this is Advanced Hardware Electromagnetic Remanence Techniques. No matter how many times data is overwritten Remanence remains. An Example: 320 Gig HDD with 999 day Internet Explorer Browser history, 46 weeks long, overwritten 2 months. 29 Recovery programs including all mentioned here, 13 Binary, Cache, and Index programs, and 6 Index.Dat Analyzer's were first attempted in recovery. Results were unintelligible. Sent to Aero Data Recovery,"Never seen anything like this". They referred HDD to ESS Data Recovery. Results: 400,000 lines of excellent readable data. HDD had been overwritten 3 to 4 passes. ESS could recover to 7 passes. To truly rid a HDD of data it must either be Magnetically Degaussed or Destroyed. There are many examples of this. M.I.T. saved data from 158 overwritten HDD.

Cost for ESS recovery, $835.00

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Can anyone shed any light on this? I know there have been people who claim anything over 1 pass is overkill, but in light of above, it gives pause & makes you wonder if it is more safe to do at least 10 passes to be safe?

I'd love to know the thoughts & opinions of everyone!

2

I know there have been people who claim anything over 1 pass is overkill...

For regular end users I'd say it's overkill especially if they're going to continue using the computer themselves.

Now on the other hand and a dash of paranoia with identity theft running rampant, etc., if I were to auction off a PC on some auction website and included the hard disk I'd most likely do something far more drastic beyond CCleaner such as using DBAN on the hard disk - but I'd still wonder if something could be snagged off a securely wiped hard disk, etc., since some file recovery software claim to find stuff others never do by looking in "special areas."

3

I haven't the time to ramble on endlessly as I usually do (but there's plenty on this subject in this forum already) but the comment above is highly speculative.

'I overwrote my disk and data was recovered' does not mean that the overwritten data was recovered.

You don't get much 'between tracks' scanning for $835, even in 2008, when that comment was written.

ESS don't claim to recover overwritten data on their website. Indeed they state that

'Files cannot be recovered once they are strictly "overwritten", but there are often fragments of the files or other clues that may contain relevant information to the case at hand, which, without computer forensics would be lost forever.'

which seems to sum up the above case and the whole overwritten data recovery myth..

There are good physical reasons why data cannot be recovered after one overwrite, and absolutely impeccable explanations why Guttman overwrites are nonsense on any but the most ancient of floppies. Gutmann said so for a start.

4

I haven't the time to ramble on endlessly as I usually do (but there's plenty on this subject in this forum already) but the comment above is highly speculative.

. . .

YYyyaahhh. :wacko:

I'm sorry. I feel guilty about the very availability of the 35 pass option. As far as I can remember, it was not available in CCleaner when I suggested it, long ago in a galaxy far far away. I'm not so conceited as to think I might have altered the course of the Piriform team, but I have in the past defended the need for the Gutmann option. Never again. Here's why:

1. The number of passes doesn't matter if you are securely deleting something from normal viewing, like by other users, snoopy room mates, etc. 1 pass will do it.

2. The number of passes doesn't matter if you are trying to hide something from the big boys, the ones with all the letters in their agency titles. Who knows for sure if any number of passes will do it? Those boys are scary good at recovering files.

3. Augeas is correct, afaik, that the Gutmann 35 pass scheme was developed for hardware that is all but non-existant now.

4. Given the uncertainty surrounding the issue, I would just replace the HD when I part w/ the computer. If I had files to conceal. That is what many professional persons (doctors, lawyers, accountants, bookies :P ) must do to avoid penalties.

Never again, Augeas, I promise. And you don't ramble, you are succinct, imho.

edit: And polite, too, I might add.

nuther edit: Found this looking at Gutmann related stuff: http://www.diskstroyer.com/

nuther edit: The cartoon in post #10 is maybe not funny: http://www.overclock...94&postcount=10