This is File Expert File Encryptor Plugin. To use this plugin, you need to have File ExpertV4.1.3 or higher version installed. Then open File Expert, go to Utilities→Plugin to apply.

Details: Use a key to encrypt your files. The encrypted file can’t be open unless you input the right key. Don't forget the key and take care of the key file. There will be no error message when you input the wrong key. The encrypted file will not open instead.