DoD 3 Pass or DoD 7 Pass Which is Best for Permanent Data Wiping

Summary: The process of permanently erasing data involves a number of protocols. You can utilise a variety of standards for erasing with data eraser software. BitRaser can erase data utilising 24 distinct international standards, including DoD 3 pass and DoD 7 pass.

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Data breach is quite common. According to Statista, there were 52 million data breaches in the second quarter of 2022. A year ago it was more than double!

There are several protocols that are followed. The DoD data wiping standard remains one of the best a quarter century after introduction.

You need to ensure that hard drives are properly erased before you let them go.

DoD 3 pass and DoD 7 pass are jargons that are thrown around by vendors when they bid for the hard drives you are selling.

What are they and what do they mean? We provide a lucid explanation that is aimed at informing the absolute layperson.

In the next few minutes you will understand:

  1. What is data erasure
  2. DoD 3 Pass – How it works
  3. Problem with DoD 3 Pass
  4. DoD 7 Pass – How it works
  5. DoD 3 pass vs DoD 7 pass – which is better
  6. BitRaser – A Certified Data Erasure Software for Every Need
  7. Impact of Larger Hard Drives on erasure

What is Data Erasure?

DoD 3 pass and DoD 7 pass are means of data erasure. They were DoD data wiping standards.

To begin with, what is data erasure? A quick explanation will make it clear.

With Windows 95, we came face to face with a wonderful new feature—Recycle Bin. Just drag and drop any file and it disappears.

No longer did we have to deal with the complex commands MS DOS imposed on us.

But have you ever thought about what happens to a document once you drag and drop it in the Recycle Bin of Windows?

Nothing much happens.

The path to the file gets deleted from the file table. The data still exists intact, but the path to it has been destroyed.

Data erasure is the actual erasure of the file—removing all the bits and bytes of 0 and 1 that came into existence when the document was created.

Data erasure is part of a larger initiative known as data sanitization, which comprises degaussing, data erasure, and physical destruction.

DoD 3 Pass – What Does It Mean?

What is the DoD data wiping standard?

The acronym stands for the United States Department of Defense.

It is quite natural that the DoD was one of the first organizations to realize the importance of data erasure. They have patents in every sphere of advanced science. Their computer systems also stored sensitive information about US troops, war games, and foreign policy.

The mention of DoD 5220.22-M (the formal name of DoD 3 pass) first appears in 1995 as part of the NISPOM or the National Industrial Security Program Operating Manual.

It specifies that a hard disk should be overwritten in a specific manner before disposal.

Pass 1 – write a binary 0 (binary 0 is not 0 but 00000000 or eight 0s for 1 byte).

Pass 2 – write a binary 1 (00000001 or seven 0s followed by a 1 for 1 byte).

Pass 3 – random ASCII character e.g. uppercase A (01000001).

Note that each is not a single character but 8 characters long since 8 bits make a byte. In computer language, a byte is a minimum storage possible. The term bit comes from binary digits since a computer can only understand 0 and 1.

The DoD 5220.22-M method has been tested extensively. It eliminates all possibilities of software-based recovery. Software-based recovery is reading a hard disk and analyzing the 0s and 1s using an algorithm to decode the data.

It is unsure if it can survive scanning by an electron microscope.

What is the Problem?

No one knows for sure if there is a problem with the DoD 3 pass.

But there has been speculation that using a highly advanced process known as Magnetic Force Microscopy data can be to some extent reconstructed from a hard drive.

It has to be pointed out that the resources required are beyond what any hacker has access to or even local law enforcement.

Even if it is possible only a nation-state using vast resources can piece back maybe a few percent of a hard drive.

What is the DoD 7 pass?

Following revisions to NISPOM, the DoD data wiping standard was upgraded to DoD 5220.22-M (E).

Instead of 3 passes, it advises the use of 7 passes.

Basically, run 3 passes twice with either a 0 pass or 1 pass in between.

Does it offer any advantages? Of course, the number of times a disk is overwritten makes it safer.

But the DoD 5220.22-M (E) has always been questioned because it is not possible to know if the time that goes into it is worth the effort.

Which is Better for Permanent Data Wiping?

At the outset, the DoD data wiping standard has changed. The latest versions of DoD 5220.22-M do not specify a method for data erasure.

When you hear that erasure as per DoD 5220.22-M, it means new data will be overwritten on the hard drive three times (or seven times as the case may be).

DoD 3 pass vs DoD 7 pass.

There are two schools of thought as to which is better.

The old school believed that more passes are always better which implies 7 passes is better than 3 passes.

The new trend, as summarized in NIST SP 800-88, prescribes that a single pass of any character is good enough. It is beyond the capacity of any forensics to recover data after a single pass (though isolated bits might be recovered).

BitRaser – A Certified Data Erasure Software for Every Need

DoD 3 pass or DoD 7 pass whatever your choice BitRaser is the ideal data erasure software to execute it.

Designed and developed by Stellar Data Recovery, BitRaser is an affordable solution for preventing data breaches from used hard drives and is intended for individuals as well as enterprises and ITADs.

BitRaser Screen

BitRaser can wipe data using 24 different global data eraser standards including DoD 3 pass and DoD 7 pass and generate an audit trail.

BitRaser can at ease set up an audit trail.

The report can be customized and has details about:

  • Time of erasure
  • Method employed
  • Name of the machine
  • Operating system

and more.

Impact of Larger Hard Drives

The growth in the size of computer hard drives is not without side effects. Storage of 2 GB was considered overkill on a 1995 computer (when DoD 5220.22-M was prescribed). Now, most enthusiasts have 1-2 TB storage in their laptops.

A thousand times larger also means a thousand times longer!

Using DoD 5220.22-M takes at least overnight and DoD 5220.22-M (E) more than a day to wipe 1 TB of data. At the time it was proposed, a 1 GB hard disk was wiped in a few hours.

Moreover, the rise of large-capacity external hard disks makes it even more time-consuming since they do not operate on a high-speed internal SATA bus but over USB 2 or USB 3.

To Summarize

Disk erasers allow you to use many different protocols for erasure, from the Gutman method (35 passes) to NIST SP 800-88 (single pass).

Neither is acceptable because they are at different extremes. Use DoD 3 pass or DoD 7 pass to be safe. It is the middle path between extremes.

For peace of mind, deploy DoD 5220.22-M (E) using BitRaser but be warned it will take a lot of time.

If you need to erase it in a few hours, then go for DoD 5220.22-M and let it run overnight.

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