nSteg is a command-line utility, used to perform LSB steganography on images. It is written in Go and make use of auyer's Steganography lib (also written in Go) for encoding/decoding purposes. At the time these lines are written, it's only supports .png images and .txt text files.
Step 1.
cd to $GOPATH/src/github directory of your Go installation and clone with the following command:
$ git clone https://github.com/niconc/nSteg.git
Step 2. Make sure you have install the library mentioned above (it's a dependency), by using:
$ go get -u github.com/auyer/steganography
Into the installed directory (I'm assuming it's $GOPATH/src/github.com/niconc/nSteg/) create 2 additional directories: images/ and messages/ which will be used to store the images and text file messages respectively. The image and text files must be reside there.
You have the following options:
Encode: The process of encoding a text file as a message into an image:
./nSteg -coding=encode -image=images/someImage.png -text=messages/someText.txt
The process creates a new image file, with the same name as the original + "_en" + .png located at the images directory.
Decode: The process of decoding an already encoded image, someImage_en.png, extract the message, saves it to file with the same name as the original text, + _en + .txt. ******
./nSteg -coding=decode -image=images/someEncodedImage_en.png
**Attention: The _en extension must exist after the file name of the image (and before the .png) in order for the decoder to recognize the file as an encoded file.