Ok, guys,
You're beginning to discuss something I actually
understand. Here's the deal:
If you record over data, the original data is
non-recoverable, except by REALLY expensive
analog recovery methods (laboratory/spy stuff).
If you only "delete" a file, only its directory
entry is affected, the data remains available
until something else steps on it.
If you "truncate" a file without overwriting the
entire thing first, the "orphaned" data is still
available at the sector level (low-level Norton
type disk editors).
If you record over a file, writing ANYTHING AT ALL
for its entire length, you will not be able to
recovery it short of analog lab procedures.
If this was not true, your hard disk would become
progressively more and more biased and, after a
year or so, unusable from all the "magnetic noise"
of recording over the same spots. This, or course,
does not happen, as we have all observed.
The military, naturally, expects the "bad guys" to
have cutting-edge, expensive analog recovery stuff,
so they overwrite multiple times to destroy any,
even absurdly small, magnetic bias.
If you want to protect your (deleted) data from
unwanted resurrection, use any one of several
file "wipe" programs.
There is a twist, though. If you create a file
(document, data table, etc.) which gets to a
certain size, and then you delete portions of
it (making it smaller), the application will
not know it's supposed to sweep up behind itself.
This is where disk "wipe" programs come in.
Disk wipe utilities can scrub the parts of the
disk not currently being used for file storage,
getting rid of leftover document fragments.
(Note, fdisk and format do NOT scrub the hard
disk surface, they just build partition, MBR,
FAT, and directory structures, and check for
bad sectors (format) on the disk. Format
*does* rewrite floppies, though.)
Further, there's a program written by Sydex which
will clean the end of the last sector in a file
or files, wiping anything past the end of the
document but inside the final sector.
But, I repeat, short of expensive analog spy
gadgets, if you overwrite the file, or the disk
sectors, EVEN ONCE, recovering the data will
be impossible.
If you fear "industrial espionage" or any other
kind of unwanted exhumation ("digging up") of
your old "deleted" files, then any of the several
utilities widely available will do just fine.
If you fear heavy duty analog spy intrusion, then
use bulk-erase (de-magnetize) techniques. Can I
sell you a bomb shelter?
Regards
Garry Hamilton
[EMAIL PROTECTED]
[EMAIL PROTECTED]
-----[ Quoted Material ]-----
Pete wrote:
>
<snip>
> military PCs must be "wiped", in addition to deleted; these
> programs repeatedly overwrite the sectors used by the now-deleted
> file with "marching" patterns of 00-ffhex to frustrate
> data-restoring spies.
<snip>
> Even the old PCTOOLS software could "revitalize" a beat-up,
> unreadable floppy.
<snip>
> So the data is stil there unless you demagnatise it or
> otherwise destroy it.
>
> Pete
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