TeleCipher

This system combines two applications, one is the client app responsible for sending files through SFTP to the receiver end and the other one needs to be installed on the computer which is receiving files.
The client app prompts users to enter the host computer IP address, sftp username and password. After a successfull connection user can choose either ROT13 Cipher or AES Encryption mechanism to encrypt a file. Later on a file upload, a dialogue box will appear and the user can send the file to the host(Additionally an indication of the encryption algorithm is also sent to the host)
The receiver application is a service that must be run before sending a file. It basically monitors any file creation event on a specific directory path. As soon as a file is received it will catch the file detect the encryption mechanism applied earlier, applies the appropriate decryption algorithm to get back the original data.

Watch this a demo video.

Here is an article on how you can create sftp user on Ubuntu.