How to Open Encrypted Filesby Sam N. Austin ; Updated September 28, 2017
Windows XP supports file encryption through EFS, the Encrypting File System. You can encrypt files with EFS so that only you and designated users can open them. You open files that you encrypted just as you would any other files. However, you cannot open files that another user encrypted with EFS, and other users cannot open files that you encrypted, unless the user trying to open the file has been added to the list of authorized users for that file. You can authorize users to open encrypted files using the Windows XP EFS management tools.
Click the "Start" button, then click the "My Computer" icon on the Start menu. This opens the My Computer window. Navigate to the encrypted file for which you want add an authorized user.
Right-click the encrypted file, then click the "Properties" link in the context menu. This opens the Properties window.
Click the "Advanced" button in the Properties window. This opens the Advanced Attributes window.
Click the "Details" button in the Advanced Attributes window. This opens the Encryption Details window.
Click the "Add" button in the Encryption Details window. This opens the "Select User" dialog box.
Click the user you want authorize to open the encrypted file, then click the "OK" button. This closes the dialog box.
Click the "OK" buttons in the Encryption Details and Advanced Attributes windows to close them. Click the "Apply" button in the Properties window, then click the "OK" button to close the window and complete the process.