On the Mac and also on iOS this application has another trick. Steganography is where the text of your message is hidden within an image. You send a picture to your friend with the text hidden within the file. It’s impossible to discern or read the text by looking at the picture. No one would have any idea the picture contains a secret message. When the application makes the Steganogram it does change the file name slightly. It adds .f5 at the end of the filename and most people wouldn’t notice that. Even if they did, it wouldn’t matter if they didn’t have the password. You can change the file name to whatever you like and the Steganogram will still function.
The steganography works really well and the only thing you need to consider is the means of transport through the Internet. There are some messaging services which compress images before sending them. If the images get compressed then the secret message is lost. The best thing to do is to test with your messaging app to see if it works or not.