Wipe Sensitive Data: How to Make Deleted Files Unrecoverable

9 Nov 2023

When you delete a file in Windows, the file is not deleted.
And many people do not seem to know about this.
👉 When you delete a file in Windows, only the entry that tells the computer where the actual file is saved will be deleted from the master file table.
In this way, the deleted file can still be recovered with data recovery software.
Those deleted files are just sitting on your hard drive until they are overwritten with new data.

Seed Phrases, Passwords, and Other Sensitive Information

If you are a cryptocurrency user, and you have ever had seed phrases or other important information stored on your computer, you may want to make sure that the information is permanently deleted.
There is a probability that in some distant future, someone will get your 'old' laptop and try to recover files.
❗ If your laptop or computer needs a repair and you take it to a repair shop, you may come across a not-so-honest person who in the process of repairing your device decides to recover deleted information and keep it for future use.
❗ If a hacker gets access to your computer, this malicious but technically competent person may try to recover deleted information in the hope of getting access to seed phrases, private keys, passwords, or any other valuable information.

Overwrite Deleted Data To Make It Irrecoverable

Windows computer users can use the cipher command to make deleted data irrecoverable.
In the picture below, the cipher command is overwriting deleted data in drive C using:
- 0x00: This is the hexadecimal representation of the number zero in computer programming
- 0xFF: This is the hexadecimal representation of the decimal number 255
- Random Numbers
This way, the original data is fully replaced by random data.
If you have never used Cipher, it may be advisable to make a backup copy before using it.
Some of us, use cipher regularly as a good practice. Because we avoid risks, even if the probability of any issue is low and running cipher takes only a few minutes.
👉 For Windows users, to learn more, please have a look at this article: 'Cipher Windows Guide'.
👉 For MacOS users, to learn more, please look at this article: 'How to: Delete Your Data Securely in MacOS'*
👉 For Linux users, to learn more, please look at this article: 'Ways to Permanently and Securely Delete Files and Directories in Linux'*
*Links courtesy of Teodor
Courtesy of @CryptoEntrepreneurs
A code snippet that can be used in a bat file to automate the process across many computer drives:

for %%F in (C D E F G H I J K L M N O P Q R S T U V W X Y Z) do 
if exist %%F: 
echo Encrypting free drive space %%F:
cipher /w:%%F:

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This is great to know. I am sure many people would think once it’s deleted and the recycle bin is emptied that the files are gone. 🙏
Ooh thank you very much for sharing this. But one question though, if I reformat the hardrive, does that work too? Of course there's quite a lot to do depending on your technical level of PCs drives and etc.
Worthy read about deleted files and it's recovery. Honestly i ws unaware of it and having concept that when I deleted any file , it went out permanently but damn I was wrong. Thanks man for wonderful write up!
This was a great article. I am going to have to check out cipher and see how it works. It is a good idea to do security checks regularly and to delete data you do not want people to be able to recover. Looking forward to the next security power up!
Thanks for the article! Beautiful and interesting