Cryptola

Cryptola is a powerful and user-friendly encryption software developed especially to protect all your online backups. The program uses a type of encryption technology designed by the National Security Agency (NSA) and published by the NIST as a U.S. Federal Information Processing Standard. It's very simple to use: just select a file, enter a password and click 'Do it!'. Cryptola modifies the file extension and converts it into a .cry file without altering the original content in any way. To unzip the new file, just open it with Cryptola and enter the password you created while encrypting it.