I'm having trouble decrypting EFS-encrypted files that were copied onto an external drive on another computer even though I have the correct certificate.

This is what I did:

  1. Enabled EFS on old computer.
  2. Backed up EFS certificate.
  3. Copied EFS-encrypted files from old computer to external drive.
  4. Connected external drive to new computer.
  5. Installed EFS certificate on new computer, making sure there was only one such certificate.
  6. Tried to decrypt the EFS-encrypted files on new computer by unchecking 'Encrypt contents to secure data' in the file's advanced properties.

When I try to decrypt it I first get the message "You will need to provide administrator permission to change these attributes" and then "An error occurred applying attributes to the file... Access is denied".

Neither the old nor the new machine is in a domain. I don't have access to the old machine any more.

Does anyone know how I can decrypt the files? It seems like it should be possible given that I have the key.

  • You probably need to take ownership of the files before you unencrypt them. – joeqwerty Aug 16 '16 at 14:20
  • I forgot to mention that I did that already. – HansA Aug 16 '16 at 21:26

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