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Can a file really be deleted forever? What exactly happens when you “delete” a file, and how easy is it to retrieve it?
You’ve probably seen it on crime dramas like CSI or NCIS: the investigators get their hands on the bad guy’s computer, and with a few strokes of the keyboard, they are able to reconstruct everything that the criminal thought he had deleted.
You might think those scenes are fake TV tech magic — and it’s true that they’re responsible for popularizing a lot of forensic myths. You can’t create pixels out of thin air to magically enhance a low-resolution image, and getting your buddy to join in on the same keyboard probably won’t help you stop a hacker in their tracks.
While some of those scenes are obviously poking fun at the ridiculousness of TV technology, recovering deleted files isn’t relegated to the realm of fiction.
Deleted files can be simple to recover if you know what you’re doing. This is because when you think you’re deleting a file, it usually stays on your computer until it’s overwritten.
The specifics of what happens when you delete a file depend on your operating system and the type of hard drive you’re using. When you delete a file on a hard drive using Windows you’re actually deleting a “pointer” to the file: a sort of bookmark that the system uses to find and retrieve your data. However, the data itself is still there, marked as free space and ready to be overwritten with new data. Until this happens, it’s completely recoverable.
For many users and most files, this system works perfectly. But if you want to prevent sensitive data from falling into the wrong hands – whether you're a government whistleblower or a everyday blogger – it’s just not enough to protect you.
Whether it’s legal files, medical information, banking details, passwords, or other personal data that you don’t want complete strangers to find out, you have a right to privacy on your own personal computer.
Here’s how to ensure that your deleted files are actually destroyed and gone forever.
Your Guide to Deleting Files Forever
Whether it contains passwords, emails, bank details or address books – chances are, your computer contains plenty of personal information about you. Though dragging and dropping documents into your computer's trash folder is easy – it doesn't mean they're actually deleted.
Here's how to ensure your deleted files permanently disappear from your hard drive.
What You Do: Right-click a file and select Delete (PC) or Move to Trash (Mac). The file is moved to your Recycle Bin (PC) or Trash folder (Mac).
What Actually Happens: The file remains on your hard drive but is simply placed in a new directory.
What You Do: Right-click the Recycle Bin/Trash folder and empty it. The file is removed from your Recycle Bin/Trash folder.
What Actually Happens: Links to the data are now deleted but information still exists on the hard drive. How much depends on the computer and operating system that you are using.
A file is only completely eliminated and becomes unrecoverable when it's overwritten with other data – in the same way that you might scribble over something with a pen.
The programs below prevent file recovery by ensuring that data is overwritten.
How to Delete a File on Your Hard Drive, Forever
Many permanent deletion programs are free and easy to use.
For PC Users
Method 1: File Shredder
File Shredder allows you to choose up to 5 different shredding algorithms of various strengths, meaning you can select the best method for deletion depending on the content involved.
Step 1: Go to fileshredder.org and click Download File Shredder. Complete all installation steps.
To delete files:
Step 2: Double-click on the File Shredder icon to drag and drop a file/folder into it
Alternatively, right-click on the file you want to shred and select File Shredder followed by Secure delete files
Method 2: Freeraser
Freeraser allows you to save the program on to a flash drive, meaning you can use it on shared computers. Although it has only a small download size, single files, entire folders, and USB drives can all be deleted permanently.
Step 1: Go to freeraser.com and click Download Freeraser. Complete all installation steps.
To delete files:
Step 2: Right-click on the Freeraser icon to select the file you want to destroy
Method 3: Eraser
Not only can Eraser delete individual files and folders, but it can also completely remove the data from an entire hard drive. Uniquely, Eraser offers you the option to schedule your shredding, meaning you can even set it to delete a file soon after it has been created.
Step 1: Go to eraser.heidi.ie and select the latest version for download. Complete all installation steps.
To delete files:
Step 2: Double-click on the Eraser icon on your desktop, followed by Erase Schedule and New Task
Alternatively, right-click on the file you want to delete and choose Eraser, followed by Erase
For Mac Users
You can permanently delete files using Mac's own Secure Empty Trash command, which is said to be up to the US Department of Defense's standards.
Step 1: Move the file you want to delete to Trash
Step 2: Go to Finder, and select Secure Empty Trash
Step 3: A warning pop-up will appear – click Secure Empty Trash
Step 4: Open Applications, select Utilities then Disk Utility
Step 5: Select the disk the deleted data is on, and click the Erase tab. Select Erase Free Space
Step 6: A pop-up will appear – select Most Secure
Your files are now securely deleted.
How to Delete a File on Your SSD
Due to the scattered way SSDs write and delete information, it's almost impossible to securely erase an individual file.
Researchers from the University of California found that trying to erase a single file on a SSD left behind anywhere from 4% to 75% of the original information.
But securely erasing data on an SSD is possible – you just have to erase the entire disk.
Some SSD manufacturers offer free software to perform a secure erase.
Have a look for the Secure Erase command from:
- Intel's Intel SSD Toolbox
- Samsung's Samsung Magician
- SanDisk's SSD Toolkit
Note: If your operating system is installed on your SSD you will need to reinstall it, as you'll be erasing your entire disk.
If your SSD doesn't come with any secure erase software, try this method instead:
ATA Secure Erase using Parted Magic
Parted Magic is compatible with most SSD drives. Prices start from $9.99.
Step 1: Download Parted Magic. It's a boot disk operating system so no installation is necessary.
Step 2: Select Disk Eraserfrom the desktop
Step 3: Select Internal: Secure Erase command writes zeroes to entire data area
Step 4: Select the disk drive you want to erase
Step 5: Type in the recommended password ‘NULL'
Step 6: Read the ATA Secure Erase Attention warning and select Yes
It can take from 40 minutes to 5 hours for your drive to be erased. Once successful, this message will pop up:
These tools will ensure that your personal information can never be retrieved (not even from yourself!).
- Ask Ars: How can I securely eras the data from my SSD drive? – arstechnica.com
- How Do I Empty or Manage the Recycle Bin? – computerhope.com
- When I Delete a File or Folder on My Computer, Where Does It Go? – computerhope.com
- Eraser – eraser.heidi.ie
- File Shredder – fileshredder.org
- Freeraser – freeraser.com
- Why SSD Drives Destroy Court Evidence, and What Can Be Done About It – forensic.belkasoft.com
- Learn How to Securely Delete Files in Windows – howtogeek.com
- How To Securely Eras Your SSD Without Destroying It – makeuseof.com
- How to Delete Something Permanently from Your Computer – mashable.com
- Powerful Tools for Home or Office – partedmagic.com
- 36 Free File Shredder Software Programs – pcsupport.about.com
- Freeraser v188.8.131.52 – pcsupport.about.com
- How to Permanently Delete Files – protectprivatedata.com
- Can You Ever Really Erase a Computer File? – slate.com
- Eraser Trusted Freeware – snapfiles.com
- File Shredder Trusted Freeware – snapfiles.com
- Freeraser Trusted Freeware – snapfiles.com
- How Do I Permanently Delete Files on Mac OSX? – stanford.edu
- Securely Erase Files in Mac OS X – techrepublic.com
- What Is a File Shredder? – topwindowstutorials.com
- Windows whole disk eras: Disk Eraser – udel.edu
- Reliably Erasing Data From Flash-Based Solid State Drives – usenix.org
- Deleting a File or Folder – windows.microsoft.com
Download this infographic.