Today we are going to stretch the previous article on steganography...with some different concept..with some different tools in other OS like in linux..
their is an popular tool for the linux OS named STEGHIDE...
it also be available for windows to...
how to download this tool in windows and linux OS ??
FOR LINUX...
press Ctr+Alt+T ,to open up your terminal window...now type
Command:
sudo aptitude install steghide
or
sudo apt-get install steghide
FOR WINDOW
go to this link and download steghide .
It is in zip format just extract the file..
http://steghide.sourceforge.net/download.php
now here is the manual to use the steghide ..you can read it for your knowledge..
but i am not going to cover all the command described in below..
but mostly 80 % commands will be used here in the demonstration.
So lets start without wasting time...
actually steghide tool is used for hiding .txt/.pdf file into images of format JPEG, BMP, WAV and AU.
Actually freely said ..their is know restriction on hiding file type...but here i am going to use only .txt format .
NOTE :
the size of the cover file (image) must be graeter than the size of embed file(file to be hide).
Before we start the demonstration..you have to place your image ,where you have to hide your secret file ,in the desktop and change you directory to Desktop..it's not recommended but it will make easy to use.
Step 1.
So first step is to check the capacity of the image that how much data it can hide.
Command :
heck how much of data we can embed into the picture.
command :
steghide info image.jpg
// in place of the image.png use the image name where you want to hide the data
step 2:
create an txt file throught the terminal/commmand prompt
command :
echo > file_name.txt “write your secret massage”
step 3.
check what is the size of the file_name.txt..
command :
du -b file_name.txt
output of this command shown in number which is the size of the txt file in byte.
26 byte
Step 4.
now let start the encryption...
command :
steghide embed -cf image.jpg -ef file_name.txt -sf text_hidden_img.jpg
now let understand what this command said..
embed – this is use for hiding the text in the image.
-cf – cover file mean where you have to hide your text file-format
-ef -embed file means which file you have to hide
-sf – it's an generated image where your text file is hidden.
Actually this one is not necessary but if you are checking how this tool work then it will be useful for understanding.
as you can see that an another named image is craeted in desktop with named.. secret_hide_img.jpg.
after the command executed it will ask for you to type your passphase...just type it.
HOW TO EXTRACT THE SECRET FILE FROM THE IMAGE
NOW HOW TO EXTRACT THE INFORMATION THROUGH THE ENCRYPTED IMAGE..
COMMAND :
steghide extract -sf < text_hidden_img.jpg>
this will ask for the passphase...give it..
again ask for the is it file exits.?
Press 'y'..
it will reaveal your secret file.
But if you want to reaveal your secret file in different name..if you don't understand see the screenshot below.
Command :
steghide extract -sf text_hidden_img.jpg -xf reveal_secert_file.txt
and you see it will reveal your file with different name.
like here with name reavealed_secret.txt
instaed of this result if you want to know about the incrypted image ,information..
you will under stand what iw anna say...
here you can see in the screenshots that..that image capacity is given.. 1.4 kb and in the next screenshot...it just tell me about the embded file information that..it's size is 26 byte.
encryption : rijndael-128, cbc
//actually this is an default encryption..if you want to know more please read manual just below..
for this information you have to write the command...
command :
steghide info <secret_hide_img.jpg>
after this it will ask that do you try to get embded file information.? just press 'y'.
tha's it .
here i wanna show some more thing that after embded file and before imbded file in image ..what it will change in image..
READ PREVIOUS ARTICLE ON STEGANOGRAPHY...
if you intrested more please read the manual...
SYNOPSIS
steghide command [ arguments ]
DESCRIPTION
Steghide is a steganography program that is able to hide
data in various kinds of image- and audio-files. The
color- respectivly sample-frequencies are not changed thus
making the embedding resistant against first-order statis
tical tests.
Features include the compression of the embedded data,
encryption of the embedded data and automatic integrity
checking using a checksum. The JPEG, BMP, WAV and AU file
formats are supported for use as cover file. There are no
restrictions on the format of the secret data.
Steghide uses a graph-theoretic approach to steganography.
You do not need to know anything about graph theory to use
steghide and you can safely skip the rest of this para
graph if you are not interested in the technical details.
The embedding algorithm roughly works as follows: At
first, the secret data is compressed and encrypted. Then a
sequence of postions of pixels in the cover file is cre
ated based on a pseudo-random number generator initialized
with the passphrase (the secret data will be embedded in
the pixels at these positions). Of these positions those
that do not need to be changed (because they already con
tain the correct value by chance) are sorted out. Then a
graph-theoretic matching algorithm finds pairs of posi
tions such that exchanging their values has the effect of
embedding the corresponding part of the secret data. If
the algorithm cannot find any more such pairs all
exchanges are actually performed. The pixels at the
remaining positions (the positions that are not part of
such a pair) are also modified to contain the embedded
data (but this is done by overwriting them, not by
exchanging them with other pixels). The fact that (most
of) the embedding is done by exchanging pixel values
implies that the first-order statistics (i.e. the number
of times a color occurs in the picture) is not changed.
For audio files the algorithm is the same, except that
audio samples are used instead of pixels.
The default encryption algorithm is Rijndael with a key
size of 128 bits (which is AES - the advanced encryption
standard) in the cipher block chaining mode. If you do not
trust this combination for whatever reason feel free to
choose another algorithm/mode combination (information
about all possible algorithms and modes is displayed by
the encinfo command). The checksum is calculated using
the CRC32 algorithm.
info, --info
Display information about a cover or stego file.
encinfo, --encinfo
Display a list of encryption algorithms and modes
that can be used. No arguments required.
version, --version
Display short version information. No arguments
required.
license, --license
Display steghide's license. No arguments required.
help, --help
Display a help screen. No arguments required.
EMBEDDING
You should use the embed command if you want to embed
secret data in a cover file. The following arguments can
be used with the embed command:
-ef, --embedfile filename
Specify the file that will be embedded (the file
that contains the secret message). Note that
steghide embeds the original file name in the stego
file. When extracting data (see below) the default
behaviour is to save the embedded file into the
current directory under its original name. If this
argument is omitted or filename is -, steghide will
read the secret data from standard input.
-cf, --coverfile filename
Specify the cover file that will be used to embed
data. The cover file must be in one of the follow
ing formats: AU, BMP, JPEG or WAV. The file-format
will be detected automatically based on header
information (the extension is not relevant). If
this argument is omitted or filename is -, steghide
will read the cover file from standard input.
-sf, --stegofile filename
Specify the name for the stego file that will be
created. If this argument is omitted when calling
steghide with the embed command, then the modifica
tions to embed the secret data will be made
directly to the cover file without saving it under
Specify the compression level. The compression
level can be any number in 1...9 where 1 means best
speed and 9 means best compression.
-Z, --dontcompress
Do not compress the secret data before embedding
it.
-K, --nochecksum
Do not embed a CRC32 checksum. You can use this if
the secret data already contains some type of
checksum or if you do not want to embed those extra
32 bits needed for the checksum.
-N, --dontembedname
Do not embed the file name of the secret file. If
this option is used, the extractor needs to specify
a filename to tell steghide where to write the
embedded data.
EXTRACTING
If you have received a file that contains a message that
has been embedded with steghide, use the extract command
to extract it. The following arguments can be used with
this command.
-sf, --stegofile filename
Specify the stego file (the file that contains
embedded data). If this argument is omitted or
filename is -, steghide will read a stego file from
standard input.
-xf, --extractfile filename
Create a file with the name filename and write the
data that is embedded in the stego file to it. This
option overrides the filename that is embedded int
the stego file. If this argument is omitted, the
embedded data will be saved to the current direc
tory under its original name.
GETTING INFORMATION ABOUT A COVER/STEGO FILE
You can use the info command to get some information about
a cover or stego file (for example the capacity). You
might want to use this if you have received a file and you
are not sure if it contains an embedded message or if you
COMMON OPTIONS
The following options can be used with all commands (where
it makes sense).
-p, --passphrase
Use the string following this argument as the
passphrase. If your passphrase contains whitespace,
you have to enclose it in quotes, for example: -p
"a very long passphrase".
-v, --verbose
Display detailed information about the status of
the embedding or extracting process.
-q, --quiet
Supress information messages.
-f, --force
Always overwrite existing files.
FILE NAME OPTIONS
All file name arguments (-cf, -ef, -sf, -xf) also accept -
as a filename which makes steghide use standard input or
standard output (whichever makes sense). Omitting the cor
responding file name argument will have the same effect as
using - with two exceptions: If -sf is omitted for the
embed command, then the modifications will be done
directly in the cover file. If -xf is omitted for extrac
tion, then the embedded data will be saved under the file
name that is embedded in the stego file. So when you want
to be sure that standard input/output is used, use - as
filename.
read my next article on steganography..
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