Windows 8 contains a built-in file encryption feature, called BitLocker, but only in the Pro or Enterprise versions. In addition, if your system does not have a Trusted Platform Module (TPM), you must use an external USB flash drive with BitLocker for it to work.
If you are concerned about other users of your system having access to your files, there has been a simple way to encrypt files and folders in every version of Windows since XP called Encrypted File Service (EFS). We will show you how to apply EFS to your files and folders.
NOTE: Files and folders you encrypt using EFS can only be decrypted using the Windows login that encrypted the file. Other users on the system will be able to see the files but will not be able to open them, even if they are running as administrator. That means that you also need to be careful you do not forget your login, or you will be locked out of your own files.
To encrypt a folder or a file, open File Explorer by clicking the File Explorer icon on the Taskbar if you are on the Desktop.
If you are on the Start screen, start typing “explorer” (without the quotes). The Search box displays and starts to list matches as you type. Click File Explorer in the list of results.
Select a file or folder to encrypt. For this example, we will use a folder. Right-click on the folder and select Properties from the popup menu.
On the General tab on the Properties dialog box, click the Advanced in the Attributes section.
On the Advanced Attributes dialog box, select the Encrypt contents to secure data check box and click OK.
Click OK on the Properties dialog box to close it.
The Confirm Attribute Changes dialog box displays. If you’re encrypting a folder, you are asked if you want to encrypt only the folder or the folder and all subfolders and files. Select the desired option and click OK. The Properties dialog box also closes.
The folder, or file, you encrypted displays in green text now. If you encrypted a folder and all its subfolders and files, any folders and files inside the main folder are also encrypted and displayed in green. Any files or folders you create in the main folder in the future are also encrypted.
You will also see a popup in the Notification Area on the Taskbar recommending that you backup your encryption key in case the original one is lost or corrupted. Click this popup to backup the key.
NOTE: If the popup message above disappeared before you could click it, click the Notification Area arrow and click the Encrypting File System icon.
Credit: Lori Kaufman