EncryptThat is a quick and effective way to encrypt or decrypt files directly from your Windows Explorer context menu (right click on a file).
The content of the encrypted file will be protected and no one can access it unless he has the encryption password.
It is free, small (475kb), portable (no installation needed), fast and easy way to protect the content of your sensitive files.
Freeware by LeeLu Soft 2014
Download EncryptThat portable (460kb) from MediaFile: