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[[!meta title="Securely delete files and clean diskspace"]]

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[[!toc levels=1]]
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<a id="why"></a>

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Why use secure deletion?
========================

**Operating systems do not actually remove the contents of a file when it is
deleted**, even after emptying the trash or explicitly removing the file, from
the command line for example.

Instead, they simply remove the file's entry from the file system directory,
because this requires less work and is therefore faster. The contents of the
file—the actual data—remain on the storage medium. The data will remain there
until the operating system reuses the space for new data.

Likewise, reformatting, repartitioning or reimaging a system is not always
guaranteed to write to every area of the disk, though all will cause the disk to
appear empty or, in the case of reimaging, empty except for the files present in
the image, to most software.

Finally, even when the storage medium is overwritten, physical properties of the
medium may make it possible to recover the previous contents. In most cases
however, this recovery is not possible by just reading from the storage device
in the usual way, but requires using laboratory techniques such as disassembling
the device and directly accessing/reading from its components.

<p class="quoted-from">Quoted from [[!wikipedia Secure_file_deletion
desc="Wikipedia: %s"]].</p>

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<a id="usb_and_ssd"></a>

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Warning about USB sticks and solid-state drives
===============================================

**The methods described below will not work as expected on USB sticks and
solid-state drives.**

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- The existing hard drive-oriented techniques for secure deletion of
  individual files are not effective.
- Overwriting twice the entire drive is usually, but not always,
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  sufficient to securely clean the drive.

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<div class="caution">
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Unfortunately, Tails does not currently allow you to perform this task
with graphical tools.

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[[!tails_todo wiping_flash_media desc="See the corresponding ticket."]]
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</div>

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For more details read, the corresponding section of the Wikipedia article on
[[!wikipedia Secure_file_deletion#Data_on_solid-state_drives desc="Secure file
deletion"]].

Securely delete files
=====================

In Tails you can securely delete files thanks to an extension of the Nautilus
file manager called [Nautilus
Wipe](http://wipetools.tuxfamily.org/nautilus-wipe.html).

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  1. Open the <span class="application">Nautilus</span> file browser, either
  from the <span class="guimenu">Places</span> menu or the <span
  class="guilabel">Computer</span> icon on the desktop.
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  1. Navigate to the folder containing the files that you want to delete.
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  1. Select the files that you want to delete with the mouse.
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  1. Right-click on the files and choose <span class="guimenuitem">Wipe</span>.
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     [[!img wipe_files.png link=no alt="Right-click&nbsp;▸ Wipe"]]
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  1. Confirm.
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  1. The deletion will start. It can last from a few seconds to several minutes,
  according to the size of the files. Be patient…
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<a id="clean_disk_space"></a>

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Securely clean available disk space
===================================

In order to clean up the contents of all files that were previously suppressed
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but not securely deleted from a disk, it is also possible to securely clean all 
the free space on the disk.
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<div class="caution">
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This method does not work as expected on solid-state drives or USB sticks.
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</div>
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The disk or the folder may or may not contain other files. Those files will not
be deleted during the operation.

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  1. Open Nautilus, either from the <span class="guimenu">Places</span> menu or
  the <span class="guilabel">Computer</span> icon on the desktop.
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  1. Go to the root of the disk that you want to clean (click on the
     disk in the left panel).
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  1. Right-click in empty space in the right panel and choose <span
     class="guimenuitem">Wipe available diskspace</span>.
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     [[!img wipe_available_diskspace.png link=no alt="Right-click&nbsp;▸ Wipe
     available diskspace"]]
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  1. Confirm.
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  1. The cleaning will start. It can last from a few minutes to a few hours,
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     according to the size of the available diskspace. Be patient…
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     Note that a file called <span
     class="filename">oooooooo.ooo</span> is created in the
     folder. <span class="application">Nautilus Wipe</span> tries to
     make it as big as possible to use all the available diskspace and
     then securely deletes it.
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<div class="caution">

This option does not delete hidden files. Previously deleted files can
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still exist in hidden trash folders: you can make them appear in
Nautilus by doing "View → Show hidden files".
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</div>