You can type a message in this application, set a 14 digit number (system clock on opening the application by default), and encrypt it through multiple cypher types. Then another person with the application will be able to paste it in, set the direction to decrypt, and press decrypt to see the real message.
Download the .rar file and then decompress it. Then, you can go into the dist folder and make a shortcut of the Secure_Messages.exe file to put where ever you like and launch the program.
Dev Note: I've had trouble with pyinstaller being detected as virus software when using --onefile to package everything into one .exe file, so I've had to create build folders/files. It's less convenient but I've compressed them so you can download it as one .rar still, sorry for the inconvenience!