demo of pixel-based steganography in an image (READ DESCRIPTION + PINNED COMMENT)

@DJ_NickyG (https://twitch.tv/DJ_NickyG) recently showed off some very basic steganography in a twitch stream by appending the data from multiple files into one new file (a .png and a .rar together, for example) where accessing the secrets was as simple as changing the file extension. I remembered hearing about a method of hiding text in images by modifying the actual pixel data of images, and decided to implement that very solution in a very short script (written in Java). This is a demo of that method in use. NOTE: The use of this method requires the distribution of a "key" image. Without the key image, the message will be un-extractable, as message extraction requires analysing the differences between the "key" and "cipher" image.