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BrutalStego some basic techniques, simple but effective steganography

For fun, I wondered, what would happen to a JPG image or an MP3 if you should add the hexadecimal code or text inside them, without a definite orientation, in short, a manual steganography.
So I decided to try translating a sentence in hex:

$ echo "Hello world! Ugh always like this example sentence:)" xxd-p

6369616f206d6f6e646f2120556666612073656d70726520717565737461
20636f6d65206672617365206573656d70696f203a290a

Getting a hexadecimal of the sentence, then opening a JPG with a hex editor I tried to paste the above code, starting at offset 11 (decimal), save the edited picture and try to see it ... okay! The picture does not show visible signs. :)

If I do the reverse:

$ echo "6369616f206d6f6e646f2120556666612073656d70726520717565737461
20636f6d65206672617365206573656d70696f203a290a" xxd-r-p Hello world! Ugh always like this example sentence:)
So I decided to automate the process of steganography and was born bsteg.sh
that report here:

#!/bin/bash
# BrutalStego - by Nanni Bassetti - http://www.nannibassetti.com -

nannib@libero.it

#
a simple steganographic tool for Linux
echo "Insert the message to hide:"
read ms

echo "Insert the file where to hide:" read fl echo "Insert the file name of the new file:"

read nfl
echo $ms > $nfl

len=$(wc -c steg.bin

1) asks the message to hide
2) Get the name of the file you want to hide the message

3) ask for the new file name changed (so as not sovrascirvere the original) 4) Create a file "steg.bin "containing the message encoded in hexadecimal 5) Calculate the length of the file steg.bin

6) Cut the" head "of the file where will you hide the message, the head is from 0 bytes to 11 bytes

7) Crop the rest of the file from byte 11 onwards 8) Chain in the file and save new pieces: head + + steg.bin restante_del_file

9) A video tells us what is the length of the encoded message and shows us the decoding, for prove that everything went well.

Eventually, someone would be enough to have the length of the encoded message eg. "112" and knowing that it must begin at byte 11, with a simple hex editor or a dd should cut piece from 11 to 112 of the file to get the original message.

tested on JPG and MP3 and everything works fine .... clearly you can also indulge parameterizing the starting point, which should not necessarily be 11. An example

friend to go the length that will decode the message?


"
Hello, but with all the mess you've done that yesterday we had to call 112?

"

Easy! ;)