About Encrypting File System (EFS)

Hello Sir,

I am using Windows 7 Ultimate Service Pack 1. I protected some of my too important files with EFS before 2 months before 1 month my laptop slows down so I decided to format it. When I format my laptop it's user and it's certificate is of ESF is on "John-Notebook" (It is user name). After formatting my laptop I put different user name "Eric-Notebook" (User name after formatting my laptop). Now when I try to open my very imp. File in .pdf it shows an error "There was an error opening this document. Access denied".

I made my new EFS certificate and when I right click the .pdf file and click properties>General(Tab)>Advanced>Details> in that user of this file is seeing John-Notebook, after that I click to Add button, after clicking Add button it shows my certificate (Eric-Notebook certificate) I click on it and pressed ok. My certificate is also added to that user box then I click ok. It see me an error "to add user to this file, you must have access to the file and write or Modify permission for it".

{Hint: (I have also tried to uncheck the "Encrypt content to secure data" but it also shows an error Access denied "You will need to provide administrator permission to change these attributes") AND ( I have no recovery of certificate of John-Notebook)}

Before formatting I was using Windows 7 Ultimate Service Pack 1 after formatting I am using Windows 7 Ultimate Service Pack 1.

Please help me it is too imp. file for me. Give me positive response an as early as you can.

Thank You

Hello Senil,

Thank you for posting your query in Microsoft Community.

  1. Did you back up the data on external hard drive before formatting the hard drive?
  2. When you encrypted the files did you backup the Encrypting File System (EFS) certificate and other Encryption key Certificate?

You can lose access to encrypted files if you install a new operating system or upgrade your current one, or if your current operating system fails. The following steps can help you regain access to encrypted files. You must have a backup copy of your encryption key and related certificate on a disc or other removable media (such as a USB flash drive) to follow the steps below.
If you encrypt data on your computer, you need a way to recover that data in case
something happens to the encryption key. If your encryption key is lost or damaged and you don't have a way to recover your data, the data is lost. You will also lose data if you store your encryption key on a smart card and the smart card is damaged or lost. To make sure you can always access your encrypted data, you should back up your encryption certificate and key.

You may refer to the suggestions provided by Paul Adare MVP on May 31, 2011.

How do I remove EFS encryption from a set of files?http://social.technet.microsoft.com/Forums/windowsserver/en-US/fbec9584-191e-4577-b046-1e5d9f04d911/how-do-i-remove-efs-encryption-from-a-set-of-files

Access the link below to know more about recovery of Encrypted files and creating and
backing up of EFS certificate:

http://technet.microsoft.com/en-us/library/cc700811.aspx

http://technet.microsoft.com/en-us/windows/how-do-i-get-started-with-the-encrypting-file-system-in-windows-7.aspx

http://support.microsoft.com/kb/223316/en-us
(this article belongs XP however, these practices can also be followed while using EFS on Windows 7)


Hope this resolves the issue. If issue persists, you can write back to us and we will be glad to assist you further.

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Hello Sir,

              First of all thanks for giving me reply. I wrote in my article that I don't have the back up of my old certificate OR key. I created new certificate OR key after formatting my laptop and I already make the back up of my new certificate.

So, I don't  have any kind of back up of old cert. OR key so I can't access my imp. files which I had protected with EFS.

 Ones again give me positive response as early as you can.

Thank You

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If you don't have a copy of the certificate then your files are forever lost.  The certificate is the encryption key,  you can't recreate the certificate, you need the certificate that was used when the files were encrypted.

Advanced EFS Data Recovery by Elcomsoft may be able to recover the certificate on the formatted drive, if it was not overwritten by other files there is a chance, even if slight,  that the certificate may still be intact.  If you cannot recover the certificate you are another one who has been had by the Delayed Recycle Bin which is the seeming inevitability of data loss when an inexperienced user encrypts his or her files.

John

Programmers are either not taught about Occam's razor or they forgot about it the following day.

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I am using Windows 7 Ultimate Service Pack 1. I protected some of my too important files with EFS. Please help me it is too imp. file for me.

I create and test backups of all of my important files. If you skipped this step and if you do not have a backup copy of your certificate then you will have to treat this unfortunate incident as a harsh lesson about backing up important files. Lots of people believe that backups are a waste of time. They will not change their minds until after they have suffered a major disaster.

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Hello Sir,

              Thanks for giving me reply. I already tested the Advance EFS Data Recovery tool to recover my imp. files. It didn't work for me:( 

Thank You 

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Hello Sir,

              Thanks for giving me reply. I already tested the Advance EFS Data Recovery tool to recover my imp. files. It didn't work for me:(

Two weeks ago: You encrypted imp. files because you wanted to prevent anyone from reading them unless he had a valid certificate. You selected a crack-proof encryption method.

Today: You ask this forum how to crack the crack-proof encryption scheme.

I see an inherent contradiction in your question.

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Your files are lost, a harsh lesson learned!

John

Programmers are either not taught about Occam's razor or they forgot about it the following day.

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:( I am crying loudly!! :(

There is no other way to recover files.

Thank You

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:( I am crying loudly!! :(

There is no other way to recover files.

Thank You

Definition: Experience = The sum of the mistakes I have made.

Conclusion: I must be a very experienced man.

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You encrypted your files because you wanted no one else to access them, they must have contained pretty sensitive data, why else would you have encrypted them?  Now you lost the certificate and you cannot access them so you want a way around the encryption, what purpose would encryption serve if there was a way around it or a backdoor to the encrypted files?


Is there another way to recover the files?  If you have access to a supercomputer or a powerful cluster you could always set it to work on brute force decryption and see how long it takes before the key can be cracked, the kind of thing the CIA or MI6 might engage in, or a computer science university student with access to powerful computing resources and 4-5 years to go for his degree...


John

Programmers are either not taught about Occam's razor or they forgot about it the following day.

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Last updated January 13, 2020 Views 1,620 Applies to: