Security of valuable data has always been a thing. Back in the days, when information had been stored in physical files, such as printed documents, the secure way of disposing such files was by the means of shredding. In 2017, however, the vast majority of data has become digital, which means there needs to be a way of removing digital data without it being recoverable. That can be done with the help of a secure file eraser.
What Is a Secure File Eraser?
Much like tossing a physical document into a trash bin doesn’t permanently destroy it, it’s the same for a digital file on your Mac — deleting it by dragging-and-dropping to Trash leaves it available for recovery. However, what you may not suspect is that even after you Empty Trash, your files can still be recovered with the help of third-party apps or specialists in data recovery. This applies to small items the same way it does to finding large files.
This is possible due to the fact, that data, when removed, isn’t fully deleted from the physical disk. You are essentially getting rid of the access point, but not the body of data itself, which remains in the sequence of “zeros and ones” on your disk. In order to completely remove the information from the disk, that data has to be overwritten. The difference between regular and secure removing of a file from your computer is that the latter overwrites your data with a run of 0 to make sure it’s completely unrecoverable.
Secure file eraser applications are utilities that have been specifically designed with the purpose of data sanitization. If you are planning to sell your computer, then file shredding software can prevent future owners from recovering deleted data or finding hidden files on your Mac.
Levels of Secure Deletion in File Shredders for Mac
Even when you choose to secure erase a piece of data from your computer, you have to understand that there are multiple data sanitization methods that vary in speed and degree of safety. There is no quick answer to which one is the best, so it’s up for you to see how they work and decide which option suits your needs. Here are a few most well-known ones.
Note: There is more in-depth information online available for free, that provides a more detailed description from a technical side of things.
Secure Erase Method
The current method is available on PATA/SATA type hard drives through the manufacturer firmware. The firmware essentially gives a set of commands to completely overwrite the data that is being removed to ensure no traces are left. Secure erase method is implemented through writing a binary one or zero. It occurs within the drive and is fairly fast in comparison with other methods.
The DoD 5220.22-M Approach
US Department of Defense method is known as DoD 5220.22-M. It is a standard developed by the Defense Security Service to permanently erase data. Unlike the Secure Erase, DoD 5220.22-M overwrites data in 3 passes and is software based.
• Pass 1: Overwrites data with a defined one/zero
• Pass 2: Overwrites data with a complementary value to the pass 1
• Pass 3: Overwrites data with a random value and confirms the write
As it takes 3 passes, the DoD 5220.22-M takes more time to complete.
The Peter Gutmann Method
The lengthiest of all is the Gutmann method. Developed in the late 1990s, it runs a set of 35 passes to ensure that the data has been permanently erased.
• Passes 1-4: Overwrite data with random values
• Passes 5-31: Overwrite data in a defined set of patterns
• Passes 32-35: Overwrite data with random values
It may seem like the Gutmann method provides maximum security as a result of the largest number of passes, however it is not entirely true. Due to the method being developed in the late 20th century, it is not completely fit for the technology in current disk drives. Depending on the encoding technology, you will need to run only a specific set of passes, but never all 35 of them. As a result, the Gutmann method, despite providing a decent level of security, is among the least efficient ones.
Trash Shredder and Other Features
Advanced data sanitization apps typically come with an additional set of features that can make data destruction even more effective and seamless. One of the features that makes life that much easier is Trash shredding. Basically, after moving all the documents you want to delete from your Mac to Trash, you can simply select and shred them directly from the bin instead of running a separate scan. Free data destruction apps usually can’t boast with this kind of functionality, however if you are on the market for a more well-rounded Mac utility (e.g. MacFly Pro), you can expect superior functionality to help keep your Mac clean and secure.
Secure Erase Hard Drive Free Space
Another notable feature is secure erase of hard drive free space. Applications that provide the option of erasing free space will apply a defined sanitization method and overwrite free hard drive space with a set of values. Overwriting free storage in this manner lets you clear out the data that has being previously removed from your Mac, but may still be available for recovery, thus, making it unrecoverable.
To wrap things up, the safety of your personal data should never be taken lightly. Regardless, whether your computer has sensitive corporate data, you are upgrading to a new drive, or simply selling an old Mac — secure erasing hard disk space should be a no-brainer. Choose the method that fits your needs, pick up an application that appeals to you the most, and begin destroying those files for good.
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Requires MacOS 10.10 (Yosemite) or later