I encrypt files all the time so having a encrypt/decrypt option on the right-click menu is very handy. To add this option to the right click menu in Vista, begin by starting Regedit.exe and then
Now, in the right side panel click on a blank space, right-click and select New > DWORD (32-bit) Value and name it EncryptionContextMenu. Next, right-click the new key and choose Modify. Finally, change the value data to 1 and click OK. Now when you right click on a file or folder you will see the encrypt/decrypt menu option.