destorying the hard drive

Better calm down there, John John. Gonna blow a gasket. If the "recoverable
using special testing" story is a fairy tale, it's a harmless and rather
useful one, don't you think? You've posted your "proof", others have posted
other info. You've made your demands clear. Think maybe that's enough?

Besides, far as I can tell, the answer's the same: "Zero-fill the hard drive
once (or thrice.)"

--
Gary S. Terhune
MS-MVP Shell/User
www.grystmill.com

"John John" wrote in message
...
Lil' Dave wrote:

As stated in another reply, zero-write utilities, for the most part, are
suitable for most purposes of preventing the locating of prior written
personal data. Forensic tools can still find such data though. These
rely on the latency of the magnetic field of each bit that may have
existed due to prior writes created by prior use.

FUD! There are no forensic tools available that can recover data on
securely wiped drives. If you think such tools exist please substantiate
your claim and post links to such tools or other verifiable information.

John

On Fri, 21 Mar 2008 23:48:43 -0300, John John
put finger to keyboard and composed:

Mike Y wrote:

Nope that's a total myth.
No drive zero-wiped to government standards has even had any data

recovered

from it.


Actually, I'd suspect the 'government standard' is a myth. As far as I
know, I've
never been able to find ANY hard reference to a standard for wiping a drive,
other than 'second/third' or a 'friend of a friend said that' kind of thing.

Which pretty well tells us a lot about your level of expertise in this
field.

US Dept of Defense Standard 5220.22-M
http://www.qsgi.com/usdod_standard_dod_522022m.htm

Before posting about hearsay and myths that you heard you should do a
bit of research.

John

I tried to locate references to "overwriting" in the Feb 28, 2006
NISPOM document but was unable to. See either of the next two URLs.

DoD 5220.22-M, "National Industrial Security Program Operating Manual
http://www.dtic.mil/whs/directives/c...ml/522022m.htm

NISPOM, National Industrial Security Program Operating Manual
reissued February 28, 2006
http://www.fas.org/sgp/library/nispom.htm

However, the following URL led me to an April 1, 2004 "DoD overprint"
of the NISPOM document:
http://www.fas.org/sgp/library/nispo...print_rev1.pdf

The DoD's NISPOM overprint has additional DoD stipulations, including
overwriting procedures. It seems to me that industry is not as
paranoid about rigorous data wiping as is the DoD. Then again, the
DoD's April Fools Day 2004 document is two years behind the current
2006 NISPOM.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

"John John" wrote in message
...
Lil' Dave wrote:

As stated in another reply, zero-write utilities, for the most part, are
suitable for most purposes of preventing the locating of prior written
personal data. Forensic tools can still find such data though. These
rely on the latency of the magnetic field of each bit that may have
existed due to prior writes created by prior use.

FUD! There are no forensic tools available that can recover data on
securely wiped drives. If you think such tools exist please substantiate
your claim and post links to such tools or other verifiable information.

John

May take months to retrieve such data after its wiped like you indicate, but
it exists. Does not rely on a previously written file table. No one is
willing to spend that much time and patience nowadays for some trivial
personal data retrieval unless paid enough. And, since there is no
guarantee sensitive data like SS#, credit card #s, bank account #s were
previously written to an unknown wiped hard drive; no one in their right
mind would spend such amount of time hunting such. That is why a simple
zero wipe is adequate.

http://www.cs.auckland.ac.nz/~pgut00...ecure_del.html


--
Dave

I certainly would expect that writing pseudorandom, or even identical, bytes
to each and every sector on the disk would make it nigh impossible to
recover anything, - IF that laboriously slow procedure was invoked. How it
could possibly be otherwise makes little sense to me - unless we operate
under the assumption that the electromagnetic writes are somewhat incomplete
(that is, the magnetic domains on the disk are not fully reversed (or
realigned) completely, but still have some very small residual leftover
effects (i.e. retentivity) from a previous write operation). (I'm an EE,
but I'm just making some basic assumptions here!).

John John wrote:
Mike Y wrote:

you will not be able to recover any data whatsoever on a wiped hard
drive, it can't be done, period!

John

And by the way, I do not work for any company that is in anyway
involved
in the sale or development of anything to do with computer technology
or
software.


Well, I do, and did. I've been involved with the 380 chip set way back,
and
I do know a bit about how it and hard drives in general work. And while
I've
not personally done it, I AM aware of the technologies involved, the
theory
behind the technologies, and the practice implementing those
technologies.
Granted, I've not heard much about the techniques since drives moved
into
the ZBR (a LOT changed when drives went that route) world with the high
speed transfers (compared to early MFM), but there's nothing in the
techniques or theory that would make it impossible other than that the
tools and techniques have to stay 'ahead of the game' the same way they
were then.

It's doable. Period!

It cannot be done! Period! It is a theory only and it has never been
proven! Not too long ago the US Department of Defense issued a tender
call for someone to provide methods to recover data from wiped drives
and no one stepped up to the plate to fill the tender request.

snip

On 24 Mar 2008 03:14:51 GMT, thanatoid put
finger to keyboard and composed:

"Bill in Co." wrote in
:

I certainly would expect that writing pseudorandom, or even
identical, bytes to each and every sector on the disk would
make it nigh impossible to recover anything, - IF that
laboriously slow procedure was invoked. How it could
possibly be otherwise makes little sense to me - unless we
operate under the assumption that the electromagnetic
writes are somewhat incomplete (that is, the magnetic
domains on the disk are not fully reversed (or realigned)
completely, but still have some very small residual
leftover effects (i.e. retentivity) from a previous write
operation). (I'm an EE, but I'm just making some basic
assumptions here!).

This idea - as *fact* - was presented in a thread with the same
subject (I wonder just HOW many of those there have been by now)
by someone a few years ago. He claimed a "residue" of whatever
is written to a HD /REMAINS/ even if you write over it a bunch
of times - something like: new drive, zero-formatted - 100%
magnetic signal retention, second write in the same sector -
95%, third 90%, etc. I pointed out that simple logic would
dictate that if anything like this was true, all drives would
fail within a few weeks of being installed. There was no reply.

Yeah, that makes sense. At the risk of taking this subject off topic,
it may be interesting to note that "hifi" VCRs record audio and video
on the same track, albeit with separate audio and video heads. The
audio information is buried deep under the video information, and is
recorded with a 30 degree azimuth angle to minimise crosstalk.
Although it's a completely different technology, and it has no
relevance to HDDs, it does demonstrate that it is possible to recover
two independent streams of information from the same magnetic track.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

From: "thanatoid"

This idea - as *fact* - was presented in a thread with the same
subject (I wonder just HOW many of those there have been by now)
by someone a few years ago. He claimed a "residue" of whatever
is written to a HD /REMAINS/ even if you write over it a bunch
of times - something like: new drive, zero-formatted - 100%
magnetic signal retention, second write in the same sector -
95%, third 90%, etc. I pointed out that simple logic would
dictate that if anything like this was true, all drives would
fail within a few weeks of being installed. There was no reply.

I think you're missing the distinction between analog and digital. HD's
record digital data as flux transitions, but the flux transitions can be
considered analog. When you read data back, the drive electronics
look for the transitions, and the timing of the transitions determine
what the data is. Distortions in the signal, as long as the drive
data-separator can still pull out the signal, will not affect what the
drive reads and reports as data. Underlying data can cause
timing distortions, but as long as the data-separator circuits detect
the transition within the window, the drive electronics will pull
out clean data. How dirty or distorted the signal is makes no
difference. In fact, it can be VERY dirty before the circuits will
loose lock and actually generate an error.

The main point of the drive electronics is to hide all the other stuff
from the user, and present to the user the data they are looking for.
It, by design, pulls out the latest and strongest signal and ignores
all else.

Lil' Dave wrote:
"John John" wrote in message
...

Lil' Dave wrote:


As stated in another reply, zero-write utilities, for the most part, are
suitable for most purposes of preventing the locating of prior written
personal data. Forensic tools can still find such data though. These
rely on the latency of the magnetic field of each bit that may have
existed due to prior writes created by prior use.

FUD! There are no forensic tools available that can recover data on
securely wiped drives. If you think such tools exist please substantiate
your claim and post links to such tools or other verifiable information.

John


May take months to retrieve such data after its wiped like you indicate, but
it exists.

No, Dave, it does not exist. No one has ever been able to do this, not
even Dr. Gutmann himself. It is nothing but a myth that started when
Perter Gutmann released his "famous" paper.

John

There is only one controlled and verifiable experiment that I know of
where data was "apparently" recovered on a wiped drive, this is the so
called "HelpHelp" test conducted by researchers at the Center for
Magnetic Recording Research at the University of California. The test
was conducted to determine the efficacy of Secure Data Erasure.

Before anyone makes assumption that this proves that data recovery is
possible on securely wiped drives they should read the papers that
detail how the test was conducted. In particular they should note the
following "skewed" factors which gave the researchers every possible
advantage in their search for the overwritten data, their mission was to
defeat secure data erasure and to help them all the odds were purposely
stacked in their favour:

1- The researchers had to know what to look for and where to look for
it, in the case of this test they were specifically told to look for the
written bits "helphelp" on a certain track on the disk. Without knowing
what to look for and where to look for it the researcher didn't have a
clue as to what they were looking at or seeing with their fancy tools!

2- The disk track where the helphelp bits were written was completely
wiped and tested before hand, this ensured a clean track and that the
only written bits on the track before the second test wipe were
"HelpHelp". As if condition 1 above wasn't skewed enough in favour of
the test, there were no other possible bits to weed through other than
the helphelp bits!

3- The researchers had to know the overwriting pattern of the wiping
software, when the overwriting was random and unknown the researchers
couldn't find the "helphelp" bits.

4- When two wipes were done on the drive the researchers couldn't find
the "helphelp" bits, the one pass wipe done for the test was hardly a
secure wipe!

What it boils down to is that in the end the test proved conclusively
that data recovery was impossible on securely wiped drives, the
effectiveness Secure Erasure was confirmed beyond the shadow of a doubt.

Here is one paper which mentions the so-called "HelpHelp" test:

Secure Erase of Disk Drive Data (PDF, 294kb)
Gordon Hughes and Tom Coughlin
http://www.tomcoughlin.com/Techpaper...20042502.p df

John


Bill in Co. wrote:

I certainly would expect that writing pseudorandom, or even identical, bytes
to each and every sector on the disk would make it nigh impossible to
recover anything, - IF that laboriously slow procedure was invoked. How it
could possibly be otherwise makes little sense to me - unless we operate
under the assumption that the electromagnetic writes are somewhat incomplete
(that is, the magnetic domains on the disk are not fully reversed (or
realigned) completely, but still have some very small residual leftover
effects (i.e. retentivity) from a previous write operation). (I'm an EE,
but I'm just making some basic assumptions here!).


John John wrote:

Mike Y wrote:


you will not be able to recover any data whatsoever on a wiped hard
drive, it can't be done, period!

John

And by the way, I do not work for any company that is in anyway
involved
in the sale or development of anything to do with computer technology
or
software.


Well, I do, and did. I've been involved with the 380 chip set way back,
and
I do know a bit about how it and hard drives in general work. And while
I've
not personally done it, I AM aware of the technologies involved, the
theory
behind the technologies, and the practice implementing those
technologies.
Granted, I've not heard much about the techniques since drives moved
into
the ZBR (a LOT changed when drives went that route) world with the high
speed transfers (compared to early MFM), but there's nothing in the
techniques or theory that would make it impossible other than that the
tools and techniques have to stay 'ahead of the game' the same way they
were then.

It's doable. Period!

It cannot be done! Period! It is a theory only and it has never been
proven! Not too long ago the US Department of Defense issued a tender
call for someone to provide methods to recover data from wiped drives
and no one stepped up to the plate to fill the tender request.

snip

You now have a case of battling scientific papers, and you're going to have
to do a lot more than just insist that you're guy's right. Or rather, you
should give it up until Gutmann himself fess's up. From where I sit, the
more you yell, the lower your credibility goes. Provide your references to
the best of your ability and then let them speak for themselves.

--
Gary S. Terhune
MS-MVP Shell/User
www.grystmill.com

"John John" wrote in message
...
Lil' Dave wrote:
"John John" wrote in message
...

Lil' Dave wrote:


As stated in another reply, zero-write utilities, for the most part, are
suitable for most purposes of preventing the locating of prior written
personal data. Forensic tools can still find such data though. These
rely on the latency of the magnetic field of each bit that may have
existed due to prior writes created by prior use.

FUD! There are no forensic tools available that can recover data on
securely wiped drives. If you think such tools exist please substantiate
your claim and post links to such tools or other verifiable information.

John


May take months to retrieve such data after its wiped like you indicate,
but it exists.

No, Dave, it does not exist. No one has ever been able to do this, not
even Dr. Gutmann himself. It is nothing but a myth that started when
Perter Gutmann released his "famous" paper.

John

I have had private email conversations with Peter Gutmann on this
subject and he has told me that he was never able to recover data on a
wiped drive, all he could ever do was show presence of previous data, he
could not tell what the previous data was. His method was offered as a
theoretical method of data recovery, he used it to reinforce the need
for secure deletion methods. Read the Epilogue in his paper. In my
conversation with him I asked him if he knew if anyone had ever used his
method to recover data on a wiped drive, to which he replied that he
knew of none who had. He knew of one person working for a hard drive
manufacturer who had done research on the matter but to his knowledge
the research led nowhere. Dr. Gutmann would not give me the name or
address of this researcher because he (the researcher) was doing this
research without his employer's knowledge or explicit consent, Peter did
not want to put this person in an "uncomfortable" position.

John

Gary S. Terhune wrote:
You now have a case of battling scientific papers, and you're going to
have to do a lot more than just insist that you're guy's right. Or
rather, you should give it up until Gutmann himself fess's up. From
where I sit, the more you yell, the lower your credibility goes. Provide
your references to the best of your ability and then let them speak for
themselves.