Why use secure deletion?

Attualmente i sistemi operativi non rimuovono i contenuti di un file quando viene cancellato anche dopo aver svuotato il cestino o aver rimosso espressamente il file per esempio tramite riga di comando.

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.

Allo stesso tempo, riformattare, ripartizionare o reimmaginare un sistema non garantisce sempre la scrittura di ogni area del disco, anche se tutto ciò farà sempre il disco vuoto o, in caso di reimmaginamento, vuoto eccetto per i file presenti nell'immagine ai principali software.

Finally, even when the storage medium is overwritten, physical properties of the medium might 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.

To learn more, see the Wikipedia article on data erasure.

Warning about USB sticks and SSDs

USB sticks and SSDs sometimes copy the same data to various memory cells to extend the lifetime of the device. USB sticks and SSDs also have 10–20% of spare memory cells for the same reason.

As a consequence, part of the data from a given file might still be written on the device even after securely deleting it.

This data could be recovered using advanced data forensics techniques, for example by professional data recovery services.

To mitigate this risk, you can:

• Encrypt the device before use, to make it hard to recover any data.

• Securely delete the entire device. Some old data might still be present in the spare memory cells.

• Physically destroy the device.

Securely deleting files

1. Apri il navigatore di File.

2. Vai nella cartella contenente i files che volete eliminare.

3. Seleziona con il mouse i files che vuoi eliminare.

4. Right-click (on Mac, click with two fingers) on the files and choose Wipe.

5. Conferma.

6. The deletion will start. It can last from a few seconds to several minutes, according to the size of the files. Be patient…

Securely cleaning available disk space

Per pulire i contenuti di tutti i files che sono stati rimossi in precedenza ma che non sono stati cancellati in maniera sicura da un disco è possibile pulire in maniera sicura tutto lo spazio libero sul disco.

The disk or the folder can contain other files. Those files will not be deleted during the operation.

1. Apri il navigatore di File.

2. Clicca sul disco che vuoi pulire nel riquadro a sinistra per accedere alla directory principale di questo disco.

3. Click on the button in the right corner of the title bar and choose Show Hidden Files.

4. If you want to empty the trash, delete the .Trash-1000 folder or similar.

5. Right-click (on Mac, click with two fingers) in empty space in the right pane and choose Wipe available diskspace.

6. Conferma.

7. The cleaning starts. It can last from a few minutes to a few hours, according to the size of the available diskspace. Be patient…

   Note that a file with a name similar to tmp.7JwHAyBvA9 is created in the folder. It is made as big as possible to use all the available diskspace and then securely deleted.

Securely erasing an entire device

1. Open the Disks utility.

   All the current storage devices are listed in the left pane.

2. Plug in the USB stick or SSD that you want to securely delete.

3. Un nuovo dispositivo appare nella lista dei dispositivi di memoria. Cliccaci:

   

4. Check that the description of the device on the right side of the screen corresponds to your device: its brand, its size, etc.

5. Click on the button in the titlebar and choose Format Disk… to erase all the existing partitions on the device.

6. Nella finestra di dialogo Formatta disco:

   • Choose to Overwrite existing data with zeroes in the Erase menu.

   • Choose Compatible with all systems and devices (MBR/DOS) in the Partitioning menu.

7. Click Format….

8. Nella finestra di conferma assicurati che il dispositivo sia corretto. Clicca Formatta per confermare.