Windows XP Encryption – How to Restore Encrypted Files After Reinstalling Windows XP

This may be an older question; but I recently had the same need.

My goal was to be comprehensive (search all files) and not require additional software, so it uses the command prompt and any text editor.

Here is what I found as a workable solution:

• open a cmd prompt
• Enter the command: cipher /s:c:\ > encryption.txt
• Open the file "encryption.txt"
  • To find encrypted folders, search for "will be encrypted"
  • To find encrypted files, search for "E" at the beginning of a line

Without parameters, Cipher lists state of the current directory and all files in it. The /s parameter tells it to recurse, and c:\ gives it the starting point. From there, "> ..." just redirects the output.

Cipher's output for encrypted files and folders look like this:

 Listing c:\Dev\Encrypted\
 New files added to this directory will be encrypted.

E Default.aspx
E Default.aspx.cs
E Default.aspx.designer.cs

Cipher's output for normal files and folders look like this:

 Listing c:\Dev\Plaintext\
 New files added to this directory will not be encrypted.

U Default.aspx
U Default.aspx.cs
U Default.aspx.designer.cs

Hope that helps.

After importing the Encryption key to other pc to access the encrypted files in that PC, will the key be stored in that system forever?

Well, as long as their Windows account exists, and as long as they don't delete the key (e.g. via the Certificate Manager, certmgr.msc). Aside from that, it does not have any self-destruct date.

If the above is true, will they be able to access other encrypted files I give to them after that?

Yes. (So, in general, it is fairly stupid to give someone else your own EFS key.)

Instead, remember that these keys are like SSL certificates, with a public half & a private half. Under Properties → Advanced there is a list of all users who should have access. So you could import someone else's public key (the certificate), and add it to the list for your files.