On the Mac OS you can use the Finder menu Secure Empty Trash... item to permanently get rid of files and folders. You may also use the Mac OS generic program Disk Utility to securely erase entire disk or a free space on internal or external disks.
On Microsoft Windows apart from Eraser described in this chapter one can also use CCleaner to securely delete files and folders from Recycle Bin. CCleaner can also wipe free space on the disk. Another recommended tool that can be used to securely delete files is Freeraser.
We would also like to recommend the following multiplatform tool: DBAN - Darik's Boot And Nuke. It is a package which you burn onto a CD and start your computer from. DBAN allows you securely delete the whole content of any hard disk that it detects, which makes it the ideal utility for bulk or emergency data destruction.
1.1 Things you should know about Eraser before you start
Eraser is used to permanently delete or wipe sensitive data from your computer. It does this by writing over the data you want to delete. You can select files or folders to be wiped in this way. Eraser will also delete copies of files that may exist in your computer without your knowledge. This includes files you have previously deleted using the standard Windows deletion method, and copies of documents you have worked on in the past.
Deleting files with Eraser can be performed on demand or scheduled to run at a specified times.
If you schedule Eraser to run at a certain time, then your computer must be switched on at the specified time or the wipe will not happen.
Once you have deleted a file using Eraser, it cannot be recovered using a file recovery program.
For greater security, you should set Eraser to overwrite files selected for deletion between 3 and 7 times.
Eraser can be used to wipe the free space off your computer. This refers to permanently wiping all past traces of work that may not have been properly deleted and could, in theory, be recoverable.
Installing Eraser is an easy and quick process. To begin installing Eraser, perform the following steps:
As described in the How-to Booklet chapter 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.
Step 1. Double click ; the Open File - Security Warning dialog box may appear. If it does, click to activate the InstallAware Wizard; after some moments, the Welcome to the InstallAware Wizard for Eraser screen will appear.
Step 2. Click to activate the License Agreement screen, and then click checkbox to enable the I accept the terms of the license agreement option, and then click again to activate the Important Information window.
Step 3. Click after reading the contents displayed in the scrolling window to activate the Destination Folder window and then click again.
Step 4. Click to activate the following screen:
Figure 1: The Select Program Folder window
Step 5. Check the Only for me (current user) option to ensure that only you are permitted to use Eraser, and then click to activate the Completing the InstallAware Wizard for Eraser window.
Step 6. Click and then click to complete the installation process, and to run Eraser as follows:
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.
Figure 3: The Eraser [On-Demand] screen displaying the Edit menu options
The Preferences: Erasing window appears as follows:
Figure 4: The Eraser Preferences: Erasing window
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 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 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 .
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.
Erasing unused disk space involves wiping all traces of previously existing files from the 'empty space' of your hard drive/portable storage device. This empty space usually contains files that were not deleted properly (please refer to the RecuvaHands-on guide and the How-to Booklet on **How to destroy sensitive information* from more information about this).
Tip: You can perform the wiping task on demand or you can schedule it to occur at a specified time.
Important: This process could take between 2 and 5 hours to complete and will slow your computer down while it operates. It maybe a good idea to run or schedule the free space wipe when you are not using your computer (or have gone home/to bed for the night).
Since we may not always remember to do this kind of computer 'housekeeping', Eraser has an option that lets you schedule a wiping task so that it runs at an appointed time every day, or one day per week.
Step 1. Click in the Eraser main screen.
Step 2. Select File > New Task as follows:
Figure 8: Selecting a New Task in the File menu
This will activate a window similar screen to Figure 4 (in which you created an on-demand task).
4.0 Differences between the Installed and Portable Versions of Eraser
Given that portable tools are not installed on a local computer, their existence and use may remain undetected. However, keep in mind that your external device or USB memory stick, and portable tools are only as safe as the computer you are using, and may risk being exposed to adware, malware, spyware and viruses.
Portable Eraser does not require the .Net Framework in order to run, and the extraction and installation time required is minimal. Aside from that, there are no other differences between Portable Eraser and the version designed to be installed on a local computer.
Step 2. Click to activate the Source Forge download page.
Step 3. Click
to save the installation file to your computer; then navigate to it.
Step 4. Double click ; the Open File - Security Warning dialog box may appear. If it does, click to activate the Eraser Portable | PortableApps.com Installer window.
Step 5. Click to activate the following screen:
Figure 2: The Choose Install Location window
Step 6. Click to activate the following screen:
Figure 3: The Browse for Folder window
Step 7. Click to create and type in a name for the newly created folder as shown below:
Figure 4: The Browse for Folder window displaying the newly created folder
Note: Choose a different name for the Portable Eraser folder, so it may appear less obvious that you are using it.
Step 8. Click to confirm the destination folder into which Portable Eraser will be extracted, and to return to the Choose Install Location window.
Step 9. Click to begin the extraction process, and then click after the extraction process has been completed.
Step 10. Navigate to your destination external drive or USB memory stick, as shown in Figure 5 below, then open it to confirm that the Portable Eraser program has been successfully extracted.
Figure 5: The Portable Eraser program extracted to the destination folder on a designated external hard drive (resized)
Step 11. Double click to launch Portable Eraser.
Please refer to the Eraser chapter to begin configuring and using it.
Q: Can I use Eraser on files on my USB memory stick?
A: Yes. You can wipe the files through using the Windows Explorer menu. And you can also wipe unused space on a USB memory stick by creating the appropriate task in Eraser.
Q: If I don't want to use Eraser anymore, is it easy to uninstall? If I do so, will it affect my computer in any way? And will my files stay deleted?
A: You can uninstall Eraser from the Start menu as follows: Start > Programs > Eraser > Uninstall Eraser. This will not affect other programs on your computer in any way, and the files you have wiped with Eraser will not be recoverable.
Q: Are there any Windows files that Eraser does not wipe?
A: All the files you can see in your computer can be wiped. Even some files that you cannot see (such as recoverable files in unused space) will be wiped if you set the right options mentioned above.
Q: Does Eraser wipe file names as well as the files themselves?
A: Yes, all parts of the file are wiped, however you should use CCleaner to wipe the recent documents list.
Q: Will anyone ever be able to access the deleted files?
A: Recovering data from files that have been overwritten is a highly complex and expensive process. It takes a disproportionate amount of time to recover a file that has only been overwritten once, let alone three to seven times. When using Eraser properly you may be sure that data has been securely deleted.
What kind of information does Eraser delete from your computer?
What do we mean when we talk about 'deleting unused space'?
How does Eraser wipe your data?
What is the minimum number of passes that we recommend you set Eraser to make?
How do you set minimum number of passes in Eraser?
How do you schedule Eraser to operate at a specific time?