Re: Unreasonable seizures (was Re: Scientology causes

1995-09-28

Sender: Karl Long <•••@••.•••>

>>Short of reformatting the drive, there is no way to actually
>>erase a file from disk.

>This is false. Anybody can use the same commonly-available disk
utilities
>(such as _Norton_) to *really* delete their files. If you want your
>deleted data to be safe from los Federales and from your
>competitors, you can install a utility that makes your normal file
>deletion command secure. What a secure deletion does is zero out all
>the bytes of the file before removing that file from the allocation
>table. This takes longer than a normal deletion, which is why it
>isn't done by default. But it can be done.

When a magnetic record such as on a hard disk is overwritten with new
data, a residual trace of the previous data still exists.  With the
right equipment and skill in its use, one can extract the previous
data.  Each subsequent overwriting reduces the likelyhood of being
able to retrieve the target data.

I don't know how many overwrites the current state-of-the-art
 equipment can recover, but it was at least three, ten years ago.

In order to make data unrecoverable, you must overwrite it several
times (ideally with random data).  Utilities such as Norton can make
it difficult to recover deleted data, but not impossible.


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 Posted by --  Andrew Oram  --  •••@••.••• --  Cambridge, Mass., USA
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