Access a EFS file created in Windows 10 with Windows 8.1

tulasikrishnai · 2017-12-08T21:11:39.000Z

I had accidentally formatted a Windows 10 system having some EFS files in it. But have the backup of only encrypted files in External HDD. Now I am having Windows 8.1. Also I have only the Old certificate folders copied on to the External HDD. When trying to access the EFS files it is giving message access denied. I had done the import of file old EFS certificate from the external HDD to the new system. Please help me in removing that Encryption done in Windows 10 to remove in Windows 8.1 using only the certificate copied

scottalanmiller · 2017-12-08T21:17:40.000Z

I would start by installing the same version of Windows 10 that you had and working from there.

dbeato · 2017-12-09T03:34:48.000Z

Welcome to the community!! I am assuming this is on the Domain the EFS? or just locally? Have you tried doing the below:

learn.microsoft.com

How To Migrate EFS Files and Certificates

https://superuser.com/questions/1261913/temporarily-read-an-efs-encrypted-folder-on-someone-elses-computer/1263036#1263036

leewilbur · 2017-12-09T05:17:43.000Z

EFS is tied to the user name (SID I believe) and password. If the system was reinstalled AND NOT part of a domain, then I think you’ve permanently lost the files. Sorry. If you have a backup and can restore the Windows 8.1 system, you MAY be able to recover the file that way.

If there’s any way to hack it today, then it’s not secure and POINTLESS to use.

If you really need that data, you may have to wait years for computers and cracking tools to advance far enough that they can break the encryption. (DES was used in the 80s and 90s and considered secure. Technology advanced and in January 1999 according to Wikipedia, it was cracked in less than a day. Wait 20 years, and EFS may be crackable in less than a day (all encryption considered good is good for now… in time it will be weak).

DoctorDNS · 2017-12-09T09:47:15.000Z

The message Access Denied Could be just a permissions issue. It would be worth viewing the file’s properties. With that said, another version of the OS is not going to be helpful. Ultimately you need the private key from the cert used to encrypt the file. Without that, I hope you have backups of the unencrypted files or a full backup of the users system that holds that private key. I suspect you need to recreate the information.