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Erasing File Data

 
 
Ertugrul Soeylemez
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      05-15-2007
"Sebastian G." <(E-Mail Removed)> (07-05-15 04:04:13):

> > > There is, and I've already told: shred does a very bad job.

> >
> > But in what way?

>
> shred doesn't care for journaling file systems. dd simply ignores any
> journal and writes to the raw partition or drive.
>
> shred doesn't care for caches. dd only hits the kernel buffers, with
> guarantees of write commitment.


*Sigh*, I'm still talking about an entire partition/disk. shred does
exactly the same as dd, just with a computed pattern instead of the
input from a file/device, and it overwrites multiple times by default.


> And for simply overwriting files or free space, there are serious
> alternatives which do the job right.


Are there any free (in terms of free speech) alternatives?


> > That wasn't meant to be special for zeroes. What if the cache
> > contains a block N with the value X and you want to write the same
> > block X to the same position N again? I don't know, but it would
> > make sense to just ignore it.

>
> If N wasn't written to the platers yet, the same would be true for
> 'shred', and a simply 'sync' would resolve the issue - and the command
> merging would be justified anyway. If N was already written, then
> there's simply no need to write it again.


However, cache hitting is unlikely in partition/disk overwriting anyway,
since with both methods you always overwrite from the first block to the
last.


Regards,
Ertugrul Söylemez.


--
Security is the one concept, which makes things in your life stay as
they are. Otto is a man, who is afraid of changes in his life; so
naturally he does not employ security.
 
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Sebastian G.
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      05-15-2007
Ertugrul Soeylemez wrote:


>> And for simply overwriting files or free space, there are serious
>> alternatives which do the job right.

>
> Are there any free (in terms of free speech) alternatives?



There's a $filesystem-tools package for about every $filesystem. There are
variants of 'rm'. For Windows, there are SDelete and Eraser.
 
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joe black
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      05-18-2007

"Bart Bailey" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> For some time I used to use 'Eraser' to overwrite files and their names
> from my drive, yet Directory Snoop reveals whatever was there. The purge
> feature in DirSnoop will remove these defunct filenames however.
> Is there any better app for doing this?
> I'm not looking for an entire drive wipe like scorch,
> just something for individual files and their FAT references.
>
> --
>
> Bart
>


Have you looked at PGP?


 
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Bart Bailey
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      05-18-2007
In Message-ID:<f2isc6$boj$(E-Mail Removed)> posted on Thu, 17
May 2007 19:34:44 -0500, joe black wrote: Begin

>Have you looked at PGP?


I have pgp658ckt09b3 on here, haven't used the free space wipe in quite
a while because it doesn't just do deleted file names but the entirety
of free space and takes a long time. It does obscure file names with a
bunch of aaaaaaa's which don't yield anything to recovery however.
The re-installed Eraser v5.6 now works just fine, didn't like v5.82

--

Bart
 
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Ertugrul Soeylemez
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      05-18-2007
Bart Bailey <(E-Mail Removed)> (07-05-18 01:42:26):

> > Have you looked at PGP?

>
> I have pgp658ckt09b3 on here, haven't used the free space wipe in
> quite a while because it doesn't just do deleted file names but the
> entirety of free space and takes a long time.


There is certainly a point in doing this. Read the thread again, but
more carefully.


Regards,
Ertugrul Söylemez.


--
Security is the one concept, which makes things in your life stay as
they are. Otto is a man, who is afraid of changes in his life; so
naturally he does not employ security.
 
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Ertugrul Soeylemez
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      05-18-2007
"Sebastian G." <(E-Mail Removed)> (07-05-15 15:25:46):

> > > And for simply overwriting files or free space, there are serious
> > > alternatives which do the job right.

> >
> > Are there any free (in terms of free speech) alternatives?

>
> There's a $filesystem-tools package for about every $filesystem. There
> are variants of 'rm'. For Windows, there are SDelete and Eraser.


Unfortunately nothing for my filesystems (reiserfs-3.6 and ext2). My
distribution's package tree includes this tool SecureDelete from the THC
magazine, but they rather look like infantile `1337 h4x0rz', so I'm not
so sure whether to use it. I wasn't able to find anything other, which
appeared to be widely tested. Eraser and SDelete don't help either,
because I don't have Windows.

However, nothing to bother. All important areas of my HD are encrypted,
including my personal files and temporary storage. It would be more
practical for an attacker to trojan my operating system and intercept
the key. But who could possibly be interested in my data that much?


Regards,
Ertugrul Söylemez.


--
Security is the one concept, which makes things in your life stay as
they are. Otto is a man, who is afraid of changes in his life; so
naturally he does not employ security.
 
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Sebastian G.
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      05-18-2007
Ertugrul Soeylemez wrote:

> "Sebastian G." <(E-Mail Removed)> (07-05-15 15:25:46):
>
>>>> And for simply overwriting files or free space, there are serious
>>>> alternatives which do the job right.
>>> Are there any free (in terms of free speech) alternatives?

>> There's a $filesystem-tools package for about every $filesystem. There
>> are variants of 'rm'. For Windows, there are SDelete and Eraser.

>
> Unfortunately nothing for my filesystems (reiserfs-3.6 and ext2).



Hm? ReiserFS-tools contain both an unerase and a secure erase tool.
Ext3tools was kinda similar.

> Eraser and SDelete don't help either, because I don't have Windows.



Tried in WINE? After all, with such clean cut code it should work quite
well, and the Filesystem IOCTLs are implemented in WINE.

> However, nothing to bother. All important areas of my HD are encrypted,
> including my personal files and temporary storage. It would be more
> practical for an attacker to trojan my operating system and intercept
> the key.



At the current state of science, subverting the client would be the ONLY attack.

> But who could possibly be interested in my data that much?


Who cares? I'd like to see my data secure from any threat, whether I do
imagine it or not. If you always practice good security, you'll never run
into any case where you accidentally chose too low security.
 
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Ertugrul Soeylemez
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      05-18-2007
"Sebastian G." <(E-Mail Removed)> (07-05-18 14:34:13):

> > > > > And for simply overwriting files or free space, there are
> > > > > serious alternatives which do the job right.
> > > >
> > > > Are there any free (in terms of free speech) alternatives?
> > >
> > > There's a $filesystem-tools package for about every
> > > $filesystem. There are variants of 'rm'. For Windows, there are
> > > SDelete and Eraser.

> >
> > Unfortunately nothing for my filesystems (reiserfs-3.6 and ext2).

>
> Hm? ReiserFS-tools contain both an unerase and a secure erase tool.
> Ext3tools was kinda similar.


I'm unable to find it. There is a filesystem debugger, checker, maker,
resizer and a configuration program (reiserfstune). No undeleter or
eraser.


> > Eraser and SDelete don't help either, because I don't have Windows.

>
> Tried in WINE? After all, with such clean cut code it should work
> quite well, and the Filesystem IOCTLs are implemented in WINE.


If I'm in the case that I need to wipe out a set of files (instead of
partitions), and I'm still unable to find good erasers for Linux, then I
might. Though, good to know that it works, if all else fails.


> > But who could possibly be interested in my data that much?

>
> Who cares? I'd like to see my data secure from any threat, whether I
> do imagine it or not. If you always practice good security, you'll
> never run into any case where you accidentally chose too low security.


Yes, that's my way of thinking. And now I have arrived at a point where
the effort of attacking my system is much larger than the value of my
data. The problem is that there are always things like wiretaps or
trojan horses, or even cameras. You should be safe, if your attacker is
Otto or Anna. But attackers like the NSA, the GRU or the Mossad will
still get into your system if they want.


Regards,
Ertugrul Söylemez.


--
Security is the one concept, which makes things in your life stay as
they are. Otto is a man, who is afraid of changes in his life; so
naturally he does not employ security.
 
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Bart Bailey
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      05-18-2007
fIn Message-ID:<f2k1gh$3t8$02$(E-Mail Removed)-online.com> posted on Fri, 18 May
2007 13:09:04 +0200, Ertugrul Soeylemez wrote: Begin

>Bart Bailey <(E-Mail Removed)> (07-05-18 01:42:26):
>
>> > Have you looked at PGP?

>>
>> I have pgp658ckt09b3 on here, haven't used the free space wipe in
>> quite a while because it doesn't just do deleted file names but the
>> entirety of free space and takes a long time.

>
>There is certainly a point in doing this. Read the thread again, but
>more carefully.
>
>
>Regards,
>Ertugrul Sylemez.


My initial concern was to 'erase' the file names from the FAT so that
there wouldn't remain any indication what type files had been there.
I have since found a solution and any diversion from that objective,
although interesting, isn't relevant.
No need to read it all again "more carefully".

--

Bart
 
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