Can I simply embed tar file inside png image? I`m tried cat file.tar image.png > secret.png, but this not working for me. does have anybody working example? it would be preferable in ruby or python
If you just want to bundle additional files with images and you don't care if people who can view the image can also access the files then this doesn't apply to you.
However, it's somewhat trivial to recover ordered data from an image using image processing techniques. What you're encoding in the image should have the following properties to keep you safe and to be difficult to discover:
The reason we do the last one is because it is very easy to detect if the encoded data stops half way down the image. You'll have an image where half has higher noise, and half doesn't. In some cases, this is visible to the naked eye, let alone to someone who knows what they're doing.
I don't know if the following libraries do all this. Rely on them at your own risk.
In any case, the original image should not be widely available. It's very easy to recover the data using the difference between the original and the steganographic image.
You can use the stegify library and command line tool to hide data in an image:
stegify encode --carrier image.png --data file.tar --result steg.png
stegify decode --carrier steg.png --result file.tar
You can use the stepic library.
It will do what you want out of the box:
stepic --encode --image-in=plain.png --data-in=data.tar --out=secret.png
to decode:
stepic --decode --image-in=secret.png --out=data.tar
You can download and install from the stepic webpage