Scrub free disk blocks

[James McKenzie]

JD wrote:
>   On 08/28/2010 05:32 PM, James McKenzie wrote:
>   
>> Steven Stern wrote:
>>     
>>> On 08/27/2010 11:25 PM, JD wrote:
>>>
>>>       
>>>>    Is there a Linux util to scrub free disk blocks and keep everything
>>>> else intact ??
>>>>
>>>>
>>>>         
>>> This really is an interested thread... but why do you want to scrub free
>>> blocks?
>>>
>>> I can think of a few reasons:
>>>
>>> 1) You're running Linux in a virtual machine. Zeroing all free space
>>> makes it easier to compress the image file.
>>>
>>> 2) You've been looking at something "bad" and want to make sure all
>>> traces of it are gone before the lawyers/cops arrive.
>>>
>>> There are probably other good reasons, but I'm stalled out here.
>>>
>>>
>>>
>>>       
There are lots of good reasons.  You have been accessing your bank 
accounts and want to give the drive to your highly intelligent prodigy 
and they know how to read a drive and recover data.  You have been using 
the drive in your business and don't want business data going home with 
you when you pull the drive and use in it your laptop.
>>>       
>> One thing is that if you expect the police on your doorstop, you are
>> screwed anyway.  There is NO truly secure method, other than complete
>> pulverization, to destroy disk data.
>>
>> If you want to clear the free space and reuse it, then the methods
>> described are sufficient.
>>
>> James McKenzie
>> SSCP 367830
>> (Yes, I could give a real technical description of why but it involves a
>> bunch of phyics and electrical stuff that usually drives folks nuts,
>> suffice it that Data Discovery and Restore of Tucson can do what I
>> describe to a hard drive that was trown into a fire and the heads were
>> melted to the disk.  The police got what they wanted, the disk had child
>> porn on it and had been 'secure erased' as well.)
>>
>>     
> It seems that at least 2 individuals on this list have made the assumption
> that hiding data, encrypting data and erasing data is for the purpose of
> hiding criminal activity. Such an assumption would put hundreds
> of millions of people, and possibly a lot more,  within these two 
> individuals'
> category of criminals or highly suspected of criminal activity.
>   
Did I say you were hiding criminal activity?  There are LOTS of 
legitimate reasons to encrypt data and to clean it off.  If you work in 
the PCI industry or for the US Federal Government, you have to do both, 
on a regular basis.  This is why the NSA has Secure Erase available.  
Other folks don't want 'lingering' data to come back and bite them.  
However, if you think that Secure Erase or any other program is going to 
completely wipe your hard drive, that is not so.  Secure Erase only 
gives the ability to reuse the disk in the same operating environment.  
That means if you were processing company proprietary data, then you 
cannot give the drive away.  It has to be physically destroyed.  That is 
the only way to ensure data is not available.
> Here we are in the 21st century and we still discover that there are
> people with such narrow minds, that they can easily pass through a
> 1 picometer wide slot.
> I am being very generous with that slot width.
>
>   
My mind is not narrow.  All I did is state "IF you are expecting the 
police on your doorstop"  not WHEN.  If you are using these for 
legitimate reasons, that is wonderful.  You are forward thinking, a lot 
better than most folks who find that they shipped their 'clean drives' 
to others only to find out they pulled a bunch of personal information 
and used it for ill intended reasons.

James McKenzie
SSCP 367830