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Secure Data Removal



 
 
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  #1  
Old December 24th 04, 02:00 PM
mcp6453
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Default Secure Data Removal

I made the mistake of asking this question in alt.computer, so my
apologies for the somewhat duplicate post. I have some hard drives that
I am donating to charity. The drives contain confidential information
belonging to clients of a law firm. I have a free utility that writes
zeros on the drive, and there are commercial utilities that do multiple
writes. However, the commercial utility I found is $30, which is more
than I want to pay unless absolutely necessary. Can someone recommend a
free or less expensive multi-wipe utility for hard drives, all space,
not just empty?
  #2  
Old December 24th 04, 03:57 PM
Irwin
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Default

I have used eraser in the past:
http://www.heidi.ie/eraser/
It is free and writes multiple patterns over the drive. Does it work?
Who really knows. I guess you take it on faith that it works, unless
you have the knowledge to try and get the data back after it is
overwritten.

Irwin

  #3  
Old December 24th 04, 05:14 PM
Arno Wagner
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Default

Previously mcp6453 wrote:
I made the mistake of asking this question in alt.computer, so my
apologies for the somewhat duplicate post. I have some hard drives that
I am donating to charity. The drives contain confidential information
belonging to clients of a law firm. I have a free utility that writes
zeros on the drive, and there are commercial utilities that do multiple
writes. However, the commercial utility I found is $30, which is more
than I want to pay unless absolutely necessary. Can someone recommend a
free or less expensive multi-wipe utility for hard drives, all space,
not just empty?


Write zeros several times. After 10 times or so it should be as
secure as 2-3 random passes.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus


  #4  
Old December 24th 04, 06:04 PM
Mike Redrobe
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Default

mcp6453 wrote:
I made the mistake of asking this question in alt.computer, so my
apologies for the somewhat duplicate post. I have some hard drives
that I am donating to charity. The drives contain confidential
information belonging to clients of a law firm. I have a free utility
that writes zeros on the drive, and there are commercial utilities
that do multiple writes. However, the commercial utility I found is
$30, which is more than I want to pay unless absolutely necessary.
Can someone recommend a free or less expensive multi-wipe utility for
hard drives, all space, not just empty?


After running one or more of these "data removal" programs, run
a few "data recovery" programs, to check nothing is there !

A data recovery company can still get data off the drive by
dismantling the drive and using specialised hardware, but if you're
that bothered, don't give the drives away, just smash the platters !

--
Mike


  #5  
Old December 24th 04, 11:03 PM
Gary L.
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Default

On Fri, 24 Dec 2004 13:00:38 GMT, mcp6453
wrote:

Can someone recommend a
free or less expensive multi-wipe utility for hard drives, all space,
not just empty?


Darik's Boot and Nuke will do the job and it is open source:

http://dban.sourceforge.net/

Make a boot floppy, then boot from it and choose the number of passes
(from one pass of zeros to 35 passes of random data). It will nuke
everything, including the MBR, partition tables, etc., but it does
take a while to run.

Someone else suggested Eraser which is fine but it runs under Windows.
I think DBAN is the best choice for your application.

- -
Gary L.
Reply to the newsgroup only
  #6  
Old December 24th 04, 11:55 PM
Arno Wagner
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Default

Previously Mike Redrobe wrote:
mcp6453 wrote:
I made the mistake of asking this question in alt.computer, so my
apologies for the somewhat duplicate post. I have some hard drives
that I am donating to charity. The drives contain confidential
information belonging to clients of a law firm. I have a free utility
that writes zeros on the drive, and there are commercial utilities
that do multiple writes. However, the commercial utility I found is
$30, which is more than I want to pay unless absolutely necessary.
Can someone recommend a free or less expensive multi-wipe utility for
hard drives, all space, not just empty?


After running one or more of these "data removal" programs, run
a few "data recovery" programs, to check nothing is there !


A data recovery company can still get data off the drive by
dismantling the drive and using specialised hardware, but if you're
that bothered, don't give the drives away, just smash the platters !


That is an unconfirmed myth with modern drives. 15 years ago this was
possible. Last year the german computer magazine c't tried to get
data recoverd after a single overwrite on a HDD. All better knowen
data recovery outfits clamied that they did not have this capability,
which means that such recovery is either impossible or very expensive
(think millions).

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus


  #7  
Old December 27th 04, 12:09 PM
Mike Redrobe
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Posts: n/a
Default


"Arno Wagner" wrote in message
...
Previously Mike Redrobe wrote:
A data recovery company can still get data off the drive by
dismantling the drive and using specialised hardware, but if you're
that bothered, don't give the drives away, just smash the platters !


That is an unconfirmed myth with modern drives. 15 years ago this was
possible. Last year the german computer magazine c't tried to get
data recoverd after a single overwrite on a HDD. All better knowen
data recovery outfits clamied that they did not have this capability,
which means that such recovery is either impossible or very expensive
(think millions).


The theory for multiple "shred" passes on these data eraser programs:

One pass is not enough to completely erase data, the hard disk heads
won't hit the same point 100% of the time (but will be within tolerance),
a few pases will "jitter" enough to hit a wider area.

With disassembly, pros could use a more precise head mechansim to
read old versions - the deleted data.

Are you saying this recovery is now limited to electron microscopy level
only ?


--
Mike





  #8  
Old December 27th 04, 02:51 PM
Arno Wagner
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Posts: n/a
Default

Previously Mike Redrobe wrote:

"Arno Wagner" wrote in message
...
Previously Mike Redrobe wrote:
A data recovery company can still get data off the drive by
dismantling the drive and using specialised hardware, but if you're
that bothered, don't give the drives away, just smash the platters !


That is an unconfirmed myth with modern drives. 15 years ago this was
possible. Last year the german computer magazine c't tried to get
data recoverd after a single overwrite on a HDD. All better knowen
data recovery outfits clamied that they did not have this capability,
which means that such recovery is either impossible or very expensive
(think millions).


The theory for multiple "shred" passes on these data eraser programs:


One pass is not enough to completely erase data, the hard disk heads
won't hit the same point 100% of the time (but will be within tolerance),
a few pases will "jitter" enough to hit a wider area.


With disassembly, pros could use a more precise head mechansim to
read old versions - the deleted data.


Are you saying this recovery is now limited to electron microscopy level
only ?


I am saying that the harddrives are close to the s/n ratio of the
surface coating. There is just not enough space to squeeze two signals
into the place of one. The "imprecise positioning" will likely get
overwritten when the neighbouring tracks are written. In addition the
head-positioning has gotten extremely accurate for writes and tracks
have gotten very slim and close together. This is not floppy
technology anymore. It is quite possible that the original signal is
just not there anymore (i.e. vanished in the bachground noise) after a
single overwrite and _nothing_ can recover it.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus


  #9  
Old December 27th 04, 05:22 PM
Alexander Grigoriev
external usenet poster
 
Posts: n/a
Default

Considering that the track pitch in modern drives is about 100 nm (and bit
length half of that), it's a miracle that they work at all!

"Arno Wagner" wrote in message
...

Are you saying this recovery is now limited to electron microscopy level
only ?


I am saying that the harddrives are close to the s/n ratio of the
surface coating. There is just not enough space to squeeze two signals
into the place of one. The "imprecise positioning" will likely get
overwritten when the neighbouring tracks are written. In addition the
head-positioning has gotten extremely accurate for writes and tracks
have gotten very slim and close together. This is not floppy
technology anymore. It is quite possible that the original signal is
just not there anymore (i.e. vanished in the bachground noise) after a
single overwrite and _nothing_ can recover it.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus




  #10  
Old December 27th 04, 05:37 PM
Al Dykes
external usenet poster
 
Posts: n/a
Default

In article .net,
Alexander Grigoriev wrote:
Considering that the track pitch in modern drives is about 100 nm (and bit
length half of that), it's a miracle that they work at all!

"Arno Wagner" wrote in message
...

Are you saying this recovery is now limited to electron microscopy level
only ?


I am saying that the harddrives are close to the s/n ratio of the
surface coating. There is just not enough space to squeeze two signals
into the place of one. The "imprecise positioning" will likely get
overwritten when the neighbouring tracks are written. In addition the
head-positioning has gotten extremely accurate for writes and tracks
have gotten very slim and close together. This is not floppy
technology anymore. It is quite possible that the original signal is
just not there anymore (i.e. vanished in the bachground noise) after a
single overwrite and _nothing_ can recover it.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus






IMO the non-classified articles that described use of electron
microscope techniques are now several years old and disk capacities
have gone from the maybe 2GB to 200GB over that time. It's safe to
assume that the issues assiciated with forensic data recovery have
changed, and it's probably harder, much harder.

IBM developed much if the head and surface technology that made our
disks possible. A google for "disk proximal recording" will get you
some information.

I have no access to any seecrreet information.

--

a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.
 




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