Steganography with Apache NiFi
Use Case
I want to hide text messages inside images. When the images arrive somewhere else, I want to extract those messages.
It let's you hide text in images, binaries in images and images in images.
I was interesting in hiding text messages in images. After seeing https://en.wikipedia.org/wiki/Turn:_Washington's_Spies I thought secret messages were cool.
So using the library, I take an image and text and hide the text in there. The library produces a new image (PNG) that has the message in it. I have a second script that extracts the text.
The images look the same to my eyes.
A future test would be to run a deep learning library or image analysis tool on the images to see if they spot the bits. They should be able to. A future NiFi tool would be to spot hidden images.
It's a fun exercise to use NiFi and it seems possible that encoding messages in images were passing through Niagra Files back in the NSA days.
Step 1: Hide Text (ExecuteStreamCommand)
Step 2: Fetch File
Step 3: UnHide Text (ExecuteStreamCommand)
The left image is the original image and the right PNG is the output image with text. The size on disk has increased at a noticeable level.
The python source code is in github and referenced below:
hide.sh
wget $1 -O img.jpg
python hidetext.py img.jpg "$2"
hidetext.py
import cv
from LSBSteg import LSBSteg
import sys
imagename=sys.argv[1]
textstring=sys.argv[2]
carrier = cv.LoadImage(imagename)
steg = LSBSteg(carrier)
steg.hideText(textstring)
steg.saveImage(imagename + ".png")
#Image that contain datas
unhide.sh
python unhidetext.py $1
unhidetext.py
import cv
from LSBSteg import LSBSteg
import sysimagename=sys.argv[1]
im = cv.LoadImage(imagename)steg = LSBSteg(im)
print steg.unhideText()
For installation, you need to download LSB-Steganography script.
OpenCV
pip install cv
Reference:
https://en.wikipedia.org/wiki/Steganography
