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I'm going to update my OS from Vista to Windows 7. I got some files (not on the OS-partition) encrypted with EFS. What happens if I install Windows 7? Will I still be able to access my files?

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up vote 4 down vote accepted

Not unless you backup your key!


  1. Click Start
  2. Click Run
  3. Enter 'mmc.exe' and click OK
  4. Click File, then Add/Remove Snap-in
  5. Click Add
  6. Select Certificates and click Add
  7. Leave selection on 'My user account' and click Finish
  8. Click Close
  9. Click OK
    1. Select Certificates - Current User in the lefthand pane of the MMC console
    2. Select Personal
    3. Select Certificates. Your personal certificate information should appear in the righthand pane of the MMC console
    4. Right-click on your certificate and select All Tasks
    5. Click Export
    6. On the Welcome screen, click Next
    7. Select 'Yes, export the private key' and click Next
    8. Leave the defaults on the Export File Format screen and click Next
    9. Enter a strong password, then re-enter it in the Confirm Password box, then click Next
    10. Enter a name to save your EFS certificate export file and browse to choose a destination folder to save it in, then click Save
    11. Click Next
    12. Click Finish

Then import it on your windows 7 installation:

  1. Right click the .pfx file that you exported and press Install PFX.
  2. Press Next and confirm you have the correct file.
  3. Press Next and enter the password for the private key.
  4. Press Next and press Place all certificates in the following store and press Browse.
  5. Press Personal, OK, and Finish.
  6. Press Yes and OK.
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It's possible the win7 "upgrade" will import this for you, and you will not need to do it yourself. – RJFalconer Aug 14 '09 at 22:09
you should always have a backup of your key wether your planning to upgrade Windows or not. – Pär Björklund Aug 15 '09 at 10:07
i did it with help of the ControlPanel, but i think the result is the same. – Marcel Benthin Aug 15 '09 at 11:25

Yes you will, as this Technet article explains:

EFS in Windows 7 supports a "mixed-mode" operation of ECC and RSA algorithms. This provides backward compatibility with EFS files that were created by using algorithms supported in previous versions of Windows. This might be useful in organizations that use RSA and also want to use the ECC algorithm to prepare for Suite B compliance.

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"Yes you will" <--but only if you backup your key – Marcel Benthin Aug 15 '09 at 11:14

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