When you encrypt or decrypt files in in Windows 7, it requires an encrypting file system (EFS) certificate issued to you by Windows. If you lose this certificate, you will not longer be able to decrypt your encrypted files. Therefore you should always keep a backup copy of your EFS certificate. Here is how you can backup your EFS certificate in Windows 7 :
- Press the key combination Windows logo key + R to open the Run dialog.
- In the Run dialog, type ReKeyWiz.exe and press Enter.
- This would open EFS Certificate Management Wizard. Click Next to continue.
- Check that you have the right certificate selected. If you do not have any certificate listed, then close the wizard and try encrypting a file. When you encrypt a file, Windows will automatically create a certificate for you. Most users will just click Next in this step.
- Choose a backup location. It is best to choose a removable disk like a USB key to keep the backup of your EFS certificate. Type in a password and click Next. The password is necessary, so that not just anybody who lays his/her hands on your backup of EFS certificate can start using it.
- Click Next in the next step if you have not changed your certificate in step #4. If you have changed to a different certificate or created a new certificate in step #4, then select all drives to apply the changes. Most users will just click Next.
- Click Close in the final information dialog which shows what you have done in the EFS Certificate Management Wizard.
