One of the ways in which you can secure your files is to use file encryption. Once you encrypt a file, it is only readable by you. Anyone else who attempts to open the file will be unsuccessful.

However, what if you want to share an encrypted file with another user? You can continue using file encryption while sharing the encrypted file with another user and here’s what you have to do:

1. Right click the encrypted file that you want to share and click Properties.
2. From the General tab, click the Advanced button.
3. From the Advanced Attributes dialog box, click the Details button.
4. Click the Add button.
5. Select the user to whom you want to grant access to the encrypted file.
6. Click OK.

Once the appropriate user has been granted permission, they will be able to view the contents of the file while preventing everyone else from doing so.
Source:
The Lockergnome Newsletter