How to decrypt encrypted Windows files

Posted on April 18, 2009 at 5:20 am

I’ve previously written several articles on how to encrypt data on your PC for security reasons, but I’ve really never written about decrypting that data. The reason I have not written any article is because even when you encrypt files on your computer, they are normally transparently decrypted for you when you view them on the same PC.

So when do you really need to decrypt files in Windows? Really only when you move the files to another computer or reformat your current computer and then copy the encrypted data back onto the new computer.

decrypt files

In either case, one thing you have to remember about encrypting and decrypting files in Windows is that you always need your encryption certificates/keys. When you turn on Encrypting File System in Windows, encryption keys are automatically created and associated with your user account.

If you reformat a computer or move the files to another computer, you first have to export the encryption keys in order to regain access to the encrypted data.

If you do not have these encryption keys, you will not be able to decrypt the data. Sadly, there is no way around it, the encryption is very strong and cannot be broken.

If you can still open the files on a computer, you want to make sure to you create a backup of the encryption keys in case the operating system ever fails and you have to copy the data to an external drive.

You can do this by following these steps:

1. Click on Start, then Run and type in mmc.exe.

decrypt encrypted files

2. Click on File and then Add/Remove Snap-in

windows decrypt files

3. Click on the Add button and choose Certificates from the list

encryption keys

4. Choose My user account and then click Finish, then Close and then OK to get back to the Console Root. Now in the tree view, expand Certificates – Current User, then Personal, then Certificates.

current user certificates

I do not have EFS enabled and that’s why I don’t have a Certificates folder under Personal.

5. Now on the right-hand side, you will see certificates listed with an Intended Purpose of Encrypting File System. 

efs certificates

6. Now right-click on the certificate and choose All Tasks and then Export. Make sure to choose “Yes, export the private key” and then click Next.

export private key

7. Now type in a password and choose a file name for the export. You will get a warning message at the end, but simply allow access.

To import this same certificate on another computer so that you can view encrypted files, follow all the steps up to 4, then right-click in the right-hand panel and choose All Tasks – Import. Select the exported certificate and follow the wizard.

You will now be able to decrypt the encrypted files on the PC. Again, it is essential that you backup your keys before you reformat your computer or before something bad happens to it! If you are encrypting files and don’t have your encryption keys backed, you are asking to lose that data! Enjoy!

» Filed Under Computer Tips

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Comments

5 Responses to “How to decrypt encrypted Windows files”

  1. Ernesto said on : April 18th, 2009 at 8:25 am

    Great post. Now… is it possible to use those encription keys on other OSs? For example, if I have encryption enabled on my windows PC, and I want to switch to linux, those keys work? If so, how can I do it?
    Also, does encryption work in dual-boot systems? Will I be able to access encrypted files using both OSs?
    Thanks!


  2. Windows Tips said on : April 19th, 2009 at 8:21 pm

    just a GREAT topic, very good job


  3. MJ said on : April 20th, 2009 at 5:06 pm

    Awesome post. Very well explained.

    Thank-you


  4. Kevin said on : September 18th, 2009 at 9:40 am

    Very helpful, thank you.

    Hopefully you can answer a follow-up question. I use a batch file and scheduler to back up my data files to a portable WD Passport USB hard-drive. I just checked and it is a FAT drive. I presume that when I export the certificate per your instructions, a drive window or dialog box will prompt me for a backup location. Is it ok if I export the certificate to the FAT USB hard-drive?

    And what happens to my encrypted files that are copied to this FAT drive, do they lose their encryption?

    Thanks


  5. Huzefa said on : November 12th, 2009 at 11:45 am

    Hi, I read ur post. But the problem i am having is I had installed Windows XP Professional on my PC and had some files were encrypted but after some time, the OS crashed and now I have installed Windows 7. however i was able to recover my data from the crashed OS, even the encrypted files. But now I am unable to access the encrypted files neither I can copy them nor play them. They are all audio files.. please help!!!!!


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