When you encrypt a file (or folder), Vista creates an encryption key. This key is vital, because if it becomes corrupted or lost, you no longer will be able to access the encrypted file. Additionally, if the encrypted files are moved to a new computer, the encrytion key will need to be imported as well or the files will not be accessible.
When you first encrypt a file, you will notice a message from the System Tray notifying you to Back up your file encrytion key. To back up an encryption key:
1. Click the icon and select Back up now. This will bring up the Certificate Export Wizard.
2. Click Next and Next again.
3. Input and confirm a Password (should be one that is easy for you to remember, but different from the one you use to login to your computer).
4. Click Next.
5. Click the Browse button and navigate to the location where you want the file saved. Input a name for the file in the Filename textbox.
6. Click the Save button.
7. Click Next.
8. Click Finish.
9. Click OK when the confirmation box appears. Place your encryption key backup file in a safe place off of the system drive of your computer. It can be burned to a cd, placed on a USB drive, etc.