Eraser - Secure File Removal

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Eraser - secure file removal

Eraser is used to permanently delete sensitive data. It can also clean a digital storage device of all recoverable

data.

Homepage

www.heidi.ie/eraser

Computer Requirements

All Windows Versions

Version used in this guide

5.86a

License

Free and Open-SourceSoftware

Installing Eraser

Follow any program-specific directions in the

Guide If there are none, simply click the link below

and choose a location to save the installer

Find the installer on your computer and double-click it

Eraser :

Required Reading

How-to Booklet chapter 6. How to destroy sensitive information

Level: 1: Beginner, 2: Average, 3: Intermediate, 4: Experienced, 5: Advanced

Time required to start using this tool: 20 minutes

What you will get in return:

The ability to permanently delete unwanted files from your computer

The ability to delete all recoverable files that are currently invisible on your computer

1.1 Things you should know about this tool 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 deletedusing the standard Windows deletion method, and copies of documents you have worked on in the past.

Deleting files with Eraser can be done on demand or scheduled to run at a specified times.1.

If you schedule Eraser to run at a certain time, then your computer must be switched on at the specifiedtime or the wipe will not happen.

2.

Once you have deleted a file using Eraser, it cannot be recovered using a file recovery program.3.

For greater security, you should set Eraser to overwrite files selected for deletion between 3 and 7 times.4.

Eraser can be used to wipe the free space off your computer. This refers to permanently wiping all pasttraces of work that may not have been properly deleted and could, in theory, have been recovered.

5.

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 erasingprocess will take. This will be especially noticeable when erasing large fi les, or wiping free space.

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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 ismade 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.

Using Eraser

3.1 How to use Eraser with Windows Explorer

It is common for people to use Eraser through the My Computer /Windows Explorer programs, rather than





through the Eraser program itself.

Step 1. Open a folder containing a file you want to delete permanently.

Step 2. Right-click on this file. Two new options appear on the drop-down list, Erase and Eraser Secure Move

as follows:

Figure 6: Erase and Eraser Secure Move options

We are going to use the Erase option to permanently delete this file.

Step 3. Select Erase from the menu.

The Confirm Erasing pop up dialog box will appear as follows :

Figure 7: The Confirm Erasing pop up dialog box

If the file displayed in the pop up dialog box is the one you want to delete permanently, perform the following

step:

Step 4. Click the Yes button.

The file will then be wiped from your system .

Warning: When you wipe a file this way, it will be deleted forever. You will not be able to retrieve it. Be sure the

files you wipe are the ones you do not want on your computer.

To securely move a file/s from one location to another (for example, from your computer to a USB memorystick):

Step 5. Select: Eraser Secure Move

You will need to answer the same warning prompt, as above, to continue.

3.2 How to Wipe Unused Disk Space

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 (seethe UndeletePlus Hands-on guide & the How-to Booklet chapter 6 from more information about this).

Step 1. Select: Start > Programs > Eraser > Eraser

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).

3.3 Using the on-Demand Task

To create an On-Demand task for wiping unused disk space , perform the following steps:

Step 1. Click:

Step 2. Select: File > New Task as follows:

Figure 8: Selecting a New Task in the File menu

The Unused space on drive option should be selected.

Step 3. Choose the drive you want to clear the free space on. (In this example, the Local Disk (C:) has been

selected. This is usually the primary hard drive on most computers.)

Figure 9: The Eraser Task Properties screen

Step 4. Click the OK button.

The task has been created and must be run, and appears in the Eraser main screen.

Step 5. Right-click the task to activate the pop-up menu as follows:





Figure 10: The Eraser screen with Run selected

Step 6. Select: Run to activate the Eraser pop up dialog box as follows:

Figure 11: The Eraser pop up dialog box

Step 7. Click the Yes button.

A progress screen appears as Eraser begins wiping the unused space as follows:

Figure 12: The Eraser screen

3.4 Using the Scheduled Task

Since we may not always remember to do this kind of computer 'housekeeping', Eraser has an option that lets

you to 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 13: Selecting a New Task in the File menu

You will see a similar screen to the one in which you created an on-demand task.

Step 3. Set these options as outlined in section 3.3 How to Use the on-Demand Tasks Option.

Figure 14: The Eraser Task Properties screen displaying the Schedule tab

Step 4. Click the Schedule tab

These options are presented in the Schedule tab.

Figure 15: The Eraser Schedule tab





Note: Use the drop-down box labelled Every to set the task to run daily, or on a certain day of the week. The

second text box sets the time which must be in 24-hour format.

Step 5. After you have you have set a time and day, click the OK button.

The scheduled task will appear as follows :

Figure 16: The Eraser Scheduled task list

Note: The computer must be switched on for the Scheduled task to run.

3.5 How to Remove a Task

After you have run either an on-demand task or a scheduled task, you may want to remove it from your task list.

To remove an on-demand task, perform the following steps:

Step 1. Click: to display the task list as follows:

Figure 17: The Eraser task list

Step 2. Select the task you want to remove. (Highlighted in blue as shown above.)

Step 3. Click:

The task will then be removed from the task list as follows:

Figure 18: The Eraser task list with the on-demand task removed

The process for removing a Scheduled Task is almost identical. To remove a scheduled task, perform the

following step:

Step 1. Click:

Repeat steps 2 and 3 described above.

FAQ and Review

Elena and Nikolai find Eraser easy enough to use, but they both realise that it is a program which should beused with care, since items which are deleted in this way cannot be recovered. They feel that it is important to

take the time to get to know the program properly before using it on a regular basis. Eraser seems to be workingfine on Elena's machine, but they both still want to know a few more things about 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: Select: Start > Programs > Eraser > UninstallEraser . 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 fi le 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.

4.1 Questions to test yourself with after completing the chapter:

What kind of information does Eraser delete from your computer?1.

What do we mean when we talk about 'deleting unused space?'2.How does Eraser wipe your data?3.

What is the minimum number of passes that we recommend you set Eraser to make?4.

How do you set minimum number of passes in Eraser?5.How do you schedule Eraser to operate at a specific time?6.

How do you delete sub folders within a folder?7.

How do you delete several files at once?8.


Documents

Eraser - Secure File Removal