Steganocats is cat meme-maker with a twist: it conceals arbitrary bytes in the images it generates. Why you would want to do this is for you to figure out—maybe you only want your friends to know where the clubhouse is, maybe your sense of irony operates in strange dimensions—but if you do, Steganocats will make the whole process, from fetching images to meme-ifying them, as easy and fun as a bag of cats.
There is a simple command line interface that will allow you to make memes via the terminal if you don't want to do things in a Python interpreter. python steganocats.py -h should get you started.
Steganocats draws a random image from the base_images/ directory to use for the base image of the meme. Use something other than the adorable furball above in your own projects.
Steganocats relies on the flickrapi package to query Flickr for images. This is an optional step; you can use whatever images you want with Steganocats by putting them in the base_images/ directory. But querying Flickr for rights-free photos already pre-tagged by attention-hungry amateur photographers is a fun and easy way to find JPGs for your needs. We (that is, I, Jake) like cats—the internet is for cats—so Steganocats defaults to searching for cat.
To query Flickr for images, you will need a Flickr API key. Once you have one, add it to _secrets.json and then remove the underscore, so that it is named secrets.json. Voilà, you may now find many cats.
The MemeWriter class is a bag of methods for hiding messages in memes. It delegates the heavy lifting of image manipulation to Pillow, and I have done my best to make sure you don't have to know a thing about image files or Pillow classes to make your memes. Each instance of MemeWriter has a mode and a flag attribute, which control the mode of the output image and the byte that is encoded to flag the location of the hidden data. MemeWriter has three main methods: write_meme for creating memes, and hide_msg and find_msg for concealing and uncovering hidden bytes.
In order to conceal bytes, the mode attribute must be set to L (greyscale) or RGBA (four-channel PNG). If you're interested in why this is or how the bytes are ensconced, I have detailed the process in the code.
The flag attribute is the byte MemeWriter uses to mark the first pixel of a row it is encoding hidden bytes into. It defaults to \n. If you want to modify the flag byte (or the process of flag generation and searching entirely), the private methods _make_flag_bytes and _find_flag will be of interest to you.
write_meme takes two arguments, fp, a file object or file-like object representing the image to be manipulated, and phrase, the text to be meme-ified.
These two messages currently taken a Pillow image object as an argument; they will be refactored to take a fp, as with write_meme. hide_msg takes hidden as an argument; hidden should be a byteliteral.
Obligatory note that steganography is not encryption; you shouldn't count on the obscurity of your hidden message keeping it secure. That said, Steganocats will happily hide your encrypted bytes in kitty memes.
v. 0.7 (March 29, 2016): It works, or should, mostly. The code is not pristine. There's only one, readily detectable mean of hiding info in images. Images are saved as PNGs.
Photo: meliha tunckanat