Can files be recovered from erased CD-RW?

.. --------------------------------------
Mike Richter, were you born with
"Scam Artist" emblazoned on your face?
--------------------------------------
( Reduced to living off the trash? )
( ... my thanks to Tim ... )

Timmy Kroesen ("Net-Trash") wrote:

**** him and the Lord of all cock rings he's led around with too...g

I heard it has left Sammy with an apparently invisible penis!

==============================================
Why Acraptec shills like Tim Kroesen are hated
==============================================

=====================
From: Nemesis
Subject: Why Acraptec shills like Tim Kroesen are hated
Date: 5/30/02

This is why people hate you so much, you ****ing cock.....**** you......

Millions of people having horrible problems with this erratic SW, and
you say the reason is that they don't know how to use a computer. And
supposedly everyone who gets the program to run is a computer genius.

If you don't want to get flamed, you arrogant asshole, try to not go out
of your way to taunt innocent people and pick fights with them, which is
exactly you do. Either change your BS attitude or you're gonna get
flamed for the rest of your stay in this group, dude.

=====================

Mike Richter wrote:

Nikos Chantziaras wrote:

As others pointed out, destroying the CD is enough (except you're dealing
with the NSA, which by the way doesn't exist...).

Anyway, since I doubt that you're dealing with the NSA, which doesn't exist,
simply overriding the previous data with 703 MB of random just should be
enough.

Actually, the NSA are pikers compared with the dedicated agencies (which
also don't exist, of course). I worked with one group which required us
to extract the memory from the computer and dissolve it in acid before
the computer could be removed from its environment.

Mike
--

http://www.mrichter.com/

That's the realization of a one liner we used to hear in the '60s:
a security classification of DBR. "Destoy Before Reading". `*8-o


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Tim Kroesen wrote:
This would conclude that there was some type of 'memory' effect when
rewritable optical media is flexed back into write capable state;
I've never heard of it discussed but if it exists than it would
theoretically enable recovery of 'erased' CDRW's just like 'erased'
magnetic media; lots harder though because of the sparring of data.

I look at it like some kind of equation. If "previous" minus "current"
equals zero, then there's nothing left. But since a CD-RW can't be burned
an infinite number of times, it must mean that the whole is not equal to
zero (we don't have 0% loss); there has to be a difference between an erase
and the original state, and this difference could be
detectable/measurable/whatever. Someone with actual expertise in this area
could give more information.

On Fri, 12 Dec 2003 23:18:15 +0200, "Nikos Chantziaras"
wrote:

Tim Kroesen wrote:
This would conclude that there was some type of 'memory' effect when
rewritable optical media is flexed back into write capable state;
I've never heard of it discussed but if it exists than it would
theoretically enable recovery of 'erased' CDRW's just like 'erased'
magnetic media; lots harder though because of the sparring of data.

I look at it like some kind of equation. If "previous" minus "current"
equals zero, then there's nothing left. But since a CD-RW can't be burned
an infinite number of times, it must mean that the whole is not equal to
zero (we don't have 0% loss); there has to be a difference between an erase
and the original state, and this difference could be
detectable/measurable/whatever. Someone with actual expertise in this area
could give more information.

Imagine that you write on a paper with a pen and then erase what you
wrote with an ink rubber: the paper will likely be different from what
it was in the beginning (some fibers will have been scratched off by
the rubber) but that may not allow you to see what was written on it
as long as it was sufficiently well erased.

So the fact that the CD-RW is not in the same state than it was before
being erased doesn't mean that you can retrieve the data that was
written on it before.

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To reply by e-mail please replace the underscore with a dot.

On Dec 11, Tim Kroesen wrote:
This would conclude that there was some type of 'memory' effect when
rewritable optical media is flexed back into write capable state;
I've never heard of it discussed but if it exists than it would
theoretically enable recovery of 'erased' CDRW's just like 'erased'
magnetic media; lots harder though because of the sparring of data.

A little off topic here, Tim, but do you know if there's any "error correction"
code included in the blocks written to a CD? In the early days of the Space
Race business (1963 or so) our group was working on "Burst error correction"
algorithms to be used for satellite communications. By now it's got to be
routinely done with a single IC.

It was a rather funny situation. I was assisting a Chinese mathematician
who was doing the burst correction work, but didn't have a security
classification. He'd come up with an algorithm, I'd go in the lab and
design a hardware equivalent and test it. I'd then report back, "It only
recovered 40%, ect" and he'd go to work again. He was never allowed to
see the full results.

BEC plus PLL improved our communications 12 db from what I remember.
They must use a BEC sort of thing in modern day Windows,,etc., HD data
management.

We also had a group that recovered magnetic data from old tapes that had been
erased and re-written upon several times. It was all over my head, then and now.

Don


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In article , says...
On Dec 11, Tim Kroesen wrote:
This would conclude that there was some type of 'memory' effect when
rewritable optical media is flexed back into write capable state;
I've never heard of it discussed but if it exists than it would
theoretically enable recovery of 'erased' CDRW's just like 'erased'
magnetic media; lots harder though because of the sparring of data.

A little off topic here, Tim, but do you know if there's any "error correction"
code included in the blocks written to a CD? In the early days of the Space
Race business (1963 or so) our group was working on "Burst error correction"
algorithms to be used for satellite communications. By now it's got to be
routinely done with a single IC.

Yes, Reed-Solomon coding

http://web.usna.navy.mil/~wdj/reed-sol.htm
http://pauillac.inria.fr/~lang/hotli...h-summary.html

(same thing that Par/QuickPar uses)

Thanks; as to another question posed; I haven't read of any 'memory
effect' whatsoever on CDRW media; without being able to 'sense the
ghost' I don't think recovery is possible after a full erasure; at least
not without extraordinary methods as yet unknown...

Tim K

"Toshi1873" wrote in message
...
In article ,
says...
On Dec 11, Tim Kroesen wrote:
This would conclude that there was some type of 'memory' effect
when
rewritable optical media is flexed back into write capable
state;
I've never heard of it discussed but if it exists than it would
theoretically enable recovery of 'erased' CDRW's just like
'erased'
magnetic media; lots harder though because of the sparring of
data.

A little off topic here, Tim, but do you know if there's any "error
correction"
code included in the blocks written to a CD? In the early days of
the Space
Race business (1963 or so) our group was working on "Burst error
correction"
algorithms to be used for satellite communications. By now it's
got to be
routinely done with a single IC.

Yes, Reed-Solomon coding

http://web.usna.navy.mil/~wdj/reed-sol.htm

http://pauillac.inria.fr/~lang/hotli...h-summary.html

(same thing that Par/QuickPar uses)

On Mon, 08 Dec 2003 22:33:08 +0000, Psaiyan
wrote in alt.comp.periphs.cdr:

Does anyone know if it is possible for someone to recover files from a
CD-RW which has been completely erased?

If so, is there any method of permanently and securely removing all
traces of the data from the medium?

Your help would be appreciated.

Overwrite completely a few times with random garbage then nuke in a
microwave oven.

Do this with the room lights off and enjoy the fireworks/lightning
show

The results are quite interesting and attractive as art