Encrypting folders and files is a way to protect them from unwanted access. Encrypting File System (EFS) is a feature of Windows that you can use to store information on your hard disk in an encrypted format. Encryption is the strongest protection that Windows provides to help you keep your information secure.
Right-click the folder or file you want to encrypt, and then click Properties.
Click the General tab, and then click Advanced.
Select the Encrypt contents to secure data check box, click OK, and then click OK again.
The first time you encrypt a folder or file, an encryption certificate is automatically created. You should back up your encryption certificate. If your certificate and key are lost or damaged and you don't have a backup, you won't be able to use the files that you have encrypted. For more information, see Back up Encrypting File System (EFS) certificate.
Right-click the folder or file you want to decrypt, and then click Properties.
Clear the Encrypt contents to secure data check box, click OK, and then click OK again.