how to make the contents of a file disappear after x numbers of days or at date

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how to make the contents of a file disappear after x numbers of days or at date

user1
Anybody know of a way to make the contents of a file (txt, html, jpeg,
png, mp3, ogg etc.) disappear after a certain number of days.

To make the whole content or a selected part of a file to disappear.

The charateristic must be hidden in the file and not to be removed by a
copy.

I should be a kind of wipe operation :-)


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Re: how to make the contents of a file disappear after x numbers of days or at date

Nils Kassube-2
user1 wrote:
> Anybody know of a way to make the contents of a file (txt, html,
> jpeg, png, mp3, ogg etc.) disappear after a certain number of days.
>
> To make the whole content or a selected part of a file to disappear.
>
> The charateristic must be hidden in the file and not to be removed by
> a copy.
>
> I should be a kind of wipe operation :-)

Can you explain what you mean with "disappear"? Should the result be an
empty file or e.g. a file with the same length and random data?


Nils

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Re: how to make the contents of a file disappear after x numbers of days or at date

user1

>> I should be a kind of wipe operation :-)
> Can you explain what you mean with "disappear"? Should the result be an
> empty file or e.g. a file with the same length and random data?


I mean the result should be an empty file (or a part of a file), where
the "wiped" data is gone and cannot be restored.


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Re: how to make the contents of a file disappear after x numbers of days or at date

Karl Auer
On Thu, 2010-09-09 at 14:04 +0000, user1 wrote:
> >> I should be a kind of wipe operation :-)
> > Can you explain what you mean with "disappear"? Should the result be an
> > empty file or e.g. a file with the same length and random data?
> I mean the result should be an empty file (or a part of a file), where
> the "wiped" data is gone and cannot be restored.

You can't create a data file that "deletes itself" - at least not in any
common operating system and not under Linux.

Some applications delete certain files automatically - for example, most
browsers manage a cache - but I assume you don't mean that sort of
thing.

I believe there are object-oriented operating systems in which such a
thing might be possible, but Linux isn't one of them.

You could create a setup in which files will be deleted automatically
based on their file date or other characteristics; even based on their
contents - for example, a cron job running periodically. However, it
would be the cron job doing the deleting. A file is itself inert.

Sounds like you are trying to out-DRM Apple :-) in which case my sincere
advice is wake up and smell the future... because it won't include you.

Why not tell us what you are actually trying to achieve? Maybe if you
told us the actual problem, we could suggest other ways to solve it.

Regards, K.

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Re: how to make the contents of a file disappear after x numbers of days or at date

Cybe R. Wizard
In reply to this post by user1
On Thu, 9 Sep 2010 14:04:06 +0000 (UTC)
user1 <[hidden email]> wrote:

>
> >> I should be a kind of wipe operation :-)
> > Can you explain what you mean with "disappear"? Should the result
> > be an empty file or e.g. a file with the same length and random
> > data?
>
>
> I mean the result should be an empty file (or a part of a file),
> where the "wiped" data is gone and cannot be restored.
>
Do you want an empty file or a deletion of the file?
If the latter, use cron.

Cybe R. Wizard
--
When Windows are opened the bugs come in.
        Winduhs

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RE: how to make the contents of a file disappear after x numbers of days or at date

Mark Widdicombe
In reply to this post by Karl Auer
From: [hidden email] [[hidden email]] On Behalf Of Karl Auer [[hidden email]]
Sent: 09 September 2010 04:32 PM
On Thu, 2010-09-09 at 14:04 +0000, user1 wrote:
> >> I should be a kind of wipe operation :-)
> > Can you explain what you mean with "disappear"? Should the result be an
> > empty file or e.g. a file with the same length and random data?
>> I mean the result should be an empty file (or a part of a file), where
>> the "wiped" data is gone and cannot be restored.

>You can't create a data file that "deletes itself" - at least not in any
>common operating system and not under Linux.

I don't see why not.  You can incorporate a routine in the file (assuming it's executable)
that would check the date and if it's greater than a certain date
calls an OS routine that will delete the file stored on disk.  It won't
effect the file in memory, but the next time the file tries to load it
won't be there.

Disclaimer
http://www.shopriteholdings.co.za/pages/1019812640/disclaimer/E-mail-Disclaimer.asp



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Re: how to make the contents of a file disappear after x numbers of days or at date

Nils Kassube-2
In reply to this post by user1
user1 wrote:
> >> I should be a kind of wipe operation :-)
> >
> > Can you explain what you mean with "disappear"? Should the result
> > be an empty file or e.g. a file with the same length and random
> > data?
>
> I mean the result should be an empty file (or a part of a file),
> where the "wiped" data is gone and cannot be restored.

Probably you can do what you want with the package wipe and a script in
/etc/cron.daily/ (or /etc/cron.hourly/) which would delete (wipe) old
files in a given directory tree. But your description is still too vague
to give more detailed advice.


Nils

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RE: how to make the contents of a file disappear after x numbers of days or at date

Karl Auer
In reply to this post by Mark Widdicombe
On Thu, 2010-09-09 at 16:52 +0200, Mark Widdicombe wrote:
> >You can't create a data file that "deletes itself" - at least not in any
> >common operating system and not under Linux.
>
> I don't see why not.  You can incorporate a routine in the file
> (assuming it's executable) that would check the date and if it's
> greater than a certain date calls an OS routine that will delete the
> file stored on disk.  It won't effect the file in memory, but the next
> time the file tries to load it won't be there.

The OP wrote about image files. Not sure where you would splice in such
a routine.

But my statement stands for ALL files in a non-object-oriented operating
system; even an executable has to be run by something outside itself. No
file can "delete itself".

Regards, K.

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Re: how to make the contents of a file disappear after x numbers of days or at date

Gilles Gravier-2
In reply to this post by Cybe R. Wizard
 Encrypt the file... and at set date, delete the key. After that, the
contents are LOST.

Gilles.

On 09/09/2010 16:47, Cybe R. Wizard wrote:

> On Thu, 9 Sep 2010 14:04:06 +0000 (UTC)
> user1 <[hidden email]> wrote:
>
>>>> I should be a kind of wipe operation :-)
>>> Can you explain what you mean with "disappear"? Should the result
>>> be an empty file or e.g. a file with the same length and random
>>> data?
>>
>> I mean the result should be an empty file (or a part of a file),
>> where the "wiped" data is gone and cannot be restored.
>>
> Do you want an empty file or a deletion of the file?
> If the latter, use cron.
>
> Cybe R. Wizard

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Re: how to make the contents of a file disappear after x numbers of days or at date

Karl Auer
On Thu, 2010-09-09 at 17:23 +0200, Gilles Gravier wrote:
> Encrypt the file... and at set date, delete the key. After that, the
> contents are LOST.

Still requires activity/smarts that are external to the file. Actually,
it just pushes the problem off a level - what is going to delete the
key? The file is still not deleting itself.

I would really like to hear what the OP actually seeks to achieve...

Regards, K.

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Re: how to make the contents of a file disappear after x numbers of days or at date

Gilles Gravier-2
 Hi!

On 09/09/2010 17:29, Karl Auer wrote:

> On Thu, 2010-09-09 at 17:23 +0200, Gilles Gravier wrote:
>> Encrypt the file... and at set date, delete the key. After that, the
>> contents are LOST.
> Still requires activity/smarts that are external to the file. Actually,
> it just pushes the problem off a level - what is going to delete the
> key? The file is still not deleting itself.
>
> I would really like to hear what the OP actually seeks to achieve...
>
> Regards, K.
>

The subject says "how to make the contents of a file disappear". Not
necessarily the actual file itself.

Now about the key. Use a proper key management system that, linked with
the file encryption system, provides access to the file automatically,
and deletes the file a the set date. This is called "assured delete".

Google for Assured Delete papers by Radia Perlman and the
"Timed-Ephemerizer".

Gilles


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desired: a DRM perpetuum mobile?

M.R.-2
In reply to this post by Karl Auer
On 09/09/2010 03:29 PM, Karl Auer wrote:
> I would really like to hear what the OP actually seeks to achieve...

He very likely wants to do some DRM-type action: if his adversary
is given ("loaned"?) only that file and nothing else, and the file
is used on a computer and operating system which the "borrower"
(i.e., the adversary, and not the file creator!) controls, he would
like the file to "self-destruct" at the expiration of the loan period.

Needless to say, in such scenario there is simply no way to achieve
what he would like to do.

If, on the other hand, the file creator controls the hardware and
the OS on which the only copy of that loaned file resides at the
point where he would like it to "disappear", any number of simple
tricks will perform the desired action.

marko

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Re: how to make the contents of a file disappear after x numbers of days or at date

Johnneylee Rollins
In reply to this post by user1
On Thu, Sep 9, 2010 at 4:20 AM, user1 <[hidden email]> wrote:
> Anybody know of a way to make the contents of a file (txt, html, jpeg,
> png, mp3, ogg etc.) disappear after a certain number of days.
>
> To make the whole content or a selected part of a file to disappear.
>
> The charateristic must be hidden in the file and not to be removed by a
> copy.
Cron. https://help.ubuntu.com/community/CronHowto

write a script to remove files. It can even have a config for a list
of files to remove at those intervals.
Also, you can check the date of the files and current time if you want
time elapsing. I personally want to switch to using the discordian
date system.

~SpaceGhost

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Re: how to make the contents of a file disappear after x numbers of days or at date

Colin Law-4
On 9 September 2010 17:32, Johnneylee Rollins
<[hidden email]> wrote:

> On Thu, Sep 9, 2010 at 4:20 AM, user1 <[hidden email]> wrote:
>> Anybody know of a way to make the contents of a file (txt, html, jpeg,
>> png, mp3, ogg etc.) disappear after a certain number of days.
>>
>> To make the whole content or a selected part of a file to disappear.
>>
>> The charateristic must be hidden in the file and not to be removed by a
>> copy.
> Cron. https://help.ubuntu.com/community/CronHowto
>
> write a script to remove files. It can even have a config for a list
> of files to remove at those intervals.
> Also, you can check the date of the files and current time if you want
> time elapsing. I personally want to switch to using the discordian
> date system.

I don't think using that date system would make any difference as the
OP just wants elapsed days.
Message timed at 17:40 BST, Boomtime, the 33rd day of Bureaucracy in
the YOLD 3176

Colin

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Re: how to make the contents of a file disappear after x numbers of days or at date

Tim H.-2
In reply to this post by user1
On 09/09/10 07:20, user1 wrote:

> Anybody know of a way to make the contents of a file (txt, html, jpeg,
> png, mp3, ogg etc.) disappear after a certain number of days.
>
> To make the whole content or a selected part of a file to disappear.
>
> The charateristic must be hidden in the file and not to be removed by a
> copy.
>
> I should be a kind of wipe operation :-)
>
>

Don't konw how to contain a "wiping" characteristic in the file itself.
  On top of that, contain the characteristic, and not be removed.  I
think your on to a new file type :)

I can only think of scripting the process by cron, or sleep commands.

Copy nothing to file:
cp /dev/null FILE
Copy nothing to file in 5 days:
sleep 432000 && cp /dev/null FILE &

Text files:
grep what_you_need FILE > NEWFILE; cat NEWFILE > FILE
tail -# FILE > NEWFILE; cat NEWFILE > FILE
...same goes for head

For the binary types, you're on your own if you want to remove certain
things from the binary.  Mass removal easy, altering binary hard.

Tim H.

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Re: how to make the contents of a file disappear after x numbers of days or at date

user1
In reply to this post by Karl Auer
 
> Why not tell us what you are actually trying to achieve? Maybe if you
> told us the actual problem, we could suggest other ways to solve it.

Lets say I want to send a picture to a person - then I do not want the
person to copy it and use it for "some purpose" - the person is not an
expert, so after a day in his posession the contents of the image
disappears - same idea with a text file?

Just an idea I got to day when walking my tour in the woods *smile*

I am constantly thinking of linux and new ideas in my subconsciouness.

In a way a kind of "virus" but its only purpose is to remove the contents
of the very file of mine, either on my computer or on somebody elses.

Life is change and developement *philosophical*


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Re: how to make the contents of a file disappear after x numbers of days or at date

Alan Pope-2
On 9 September 2010 19:03, user1 <[hidden email]> wrote:
> Lets say I want to send a picture to a person - then I do not want the
> person to copy it and use it for "some purpose" - the person is not an
> expert, so after a day in his posession the contents of the image
> disappears - same idea with a text file?
>

You're basically describing DRM, nothing more.

http://en.wikipedia.org/wiki/Digital_rights_management

Examples of which:-

http://www.fileopen.com/products/fileopen_pdf_control/
http://www.locklizard.com/pdf_security.htm

I'll let others pass comment on the morality and effectiveness of such
an idea :)

Cheers,
Al.

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Re: how to make the contents of a file disappear after x numbers of days or at date

user1
> You're basically describing DRM, nothing more.

I was meaning text, html and jpeg files and NOT pdf files

> http://en.wikipedia.org/wiki/Digital_rights_management

> http://www.fileopen.com/products/fileopen_pdf_control/
> http://www.locklizard.com/pdf_security.htm

Pdf was not included in my mind in my question as I find pdf clumsy to
reading.

99.9 pct of the time i am using text, html -and jpeg files.

My main idea was to give the contents of a file a very short living time.



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Re: how to make the contents of a file disappear after x numbers of days or at date

Alan Pope-2


On 10 Sep 2010, at 06:49, user1 <[hidden email]> wrote:

>> You're basically describing DRM, nothing more.
>
> I was meaning text, html and jpeg files and NOT pdf files
>

That was just an example to illustrate my point. The fact remains what you're describing is DRM. So you'd really need to wrap the files up in some other  format to enforce this.

Al.
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Re: how to make the contents of a file disappear after x numbers of days or at date

Patton Echols
In reply to this post by user1
user1 wrote:

>  
>  
>> Why not tell us what you are actually trying to achieve? Maybe if you
>> told us the actual problem, we could suggest other ways to solve it.
>>    
>
> Lets say I want to send a picture to a person - then I do not want the
> person to copy it and use it for "some purpose" - the person is not an
> expert, so after a day in his posession the contents of the image
> disappears - same idea with a text file?
>
>  

I don't know a solution.  But have a memory that may further your thinking.

I seem to recall a version of PGP (under DOS) years ago that allowed a
user to encrypt a file into an executable wrapper.  When executed, the
wrapper would spawn a viewer in "protected memory" that prevented
copying.  The trick was that the wrapper could be set with an expiration
date.  Execution of the wrapper would fail after that date.

I have no idea if anything still exists or ever existed for linux.  The
problem with such a system is that I can think of several possible work
arounds.

Good luck

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