How to Configure Eraser

As described in the How-to Booklet chapter 6. Destroying Sensitive Information, Eraser wipes data from your hard disk by overwriting it with random information. The more times you overwrite the data, the less likely that it will be recovered.

Note: It is recommended that you overwrite the data at least three times.

Tip: Each overwrite or 'pass' takes time and therefore, the more passes you make, the longer the erasing process will take. This will be especially noticeable when erasing large files, or wiping free space.

The number of passes can be set by accessing the Preferences: Erasing menu.

Step 1. Select: Edit > Preferences > Erasing as follows:

Figure 1: The Eraser [On-demand] screen displaying the Edit menu options

The Preferences: Erasing screen appears as follows:

Figure 2: The Eraser Preferences: Erasing screen

The Preferences: Erasing screen describes how the files are to be overwritten.

Description: This column lists the name of the overwrite procedure.

Passes: This column lists how many times the data will be overwritten.

In this example, we will overwrite our data using the Pseudorandom Data method. By default, only one pass is made when using this option. However, for extra security we will increase the number of passes.

Step 2. Select the # 4 Pseudorandom Data option as shown in Figure 2.

Step 3. Click the Edit button to activate the Passes screen as follows:

Figure 3: The Eraser Passes screen

Step 4. Set the number of passes to between three and seven (remember the time/security trade-off).

Step 5. Click the OK button to return to the Passes screen.

# 4 Pseudorandom Data should now resemble the following:

Figure 4: The Eraser Erase screen with pane showing item 4 selected

Tip: Make sure the check boxes labelled Cluster Tip Area and Alternate Data Streams are checked as follows (they are checked by default):

Figure 5: The Eraser Cluster Tip Area and Alternate Data Streams check boxes in default mode

• Cluster Tip Area: A computer hard disk is divided into small segments called 'clusters'. Usually, a file spans several clusters, and often a file will not completely fill the last cluster. The unused space on this last cluster is called the cluster tip area. This cluster tip area may contain sensitive information from the other file that was written over this cluster before and occupied more of the cluster. Information from a cluster tip may be readable by a data recovery specialist. So, check the Cluster Tip Area check box for greater security.
• Alternate Data Streams: When a file is stored on your computer, it may come in different parts. For example, this text contains both text and images. These would be stored on your computer in different locations or 'streams'. So, check the Alternate Data Streams check box to ensure that all data associated with the file is deleted.

Step 6. Click the OK button.

You have now set the overwrite method for Eraser to wipe files. You should also set the same options for the Unused Disk Space feature that appears on the next tab in the Preferences: Erasing screen. However, you may set the number of passes to a reasonable figure -- taking into consideration that a free-space wipe will take around two hours per pass.