I have encrypted some files (in a separate partition from systems) on my laptop. Due to some problems with the OS, I reinstalled Windows XP. Now I cannot open the files that I encrypted. I tried the program "Advanced EFS Data Recovery" but didn't get any results. Is there a way to decrypt my files?
When you encrypt files an EFS certificate is created and its public key used during the encryption process. The related private key must be available in order to decrypt the files. Both certificate and private key are stored in the profile of the user who encrypts the files. When you reinstall XP, you have removed the user account, and probably the profile files. Hence, unless you backed up the keys, you have no access. you cannot decrypt the files.
Advanced EFS Data Recovery is a third party program which claims to be able to help you recover these EFS keys if the keys are still somewhere on the hard drive. I have not been successful in using it either. That does not mean that it doesn't work, just that you and I have not been able to gain any help from it. It does not work in the circumstances that we tried it in.
Dig Deeper on Windows 10 security and management