Today, I'm going to teach you about steganography.  Now I know what some people might say - isn't that just a bunch of jumbled nonsense, and isn't steganalysis like, the opposite of crypto-analysis?

To that, I'd like to say... sort of!

First of, I want you explain to you, just what is Steg and what does steganalysis entails. We will dive deep to the concept behind steganalysis, including different types, its techniques, tools and challenges associated with the subject.

So, buckle in! We have a whole new realm to cover. I want you to know by the time we finish with steganography, I'll make you proficient on steganographic techniques used for secure communications. You might want a paper, or two, or three for a future cryptography exam (you can get them online or borrow from friends, just say no to copyright).

Steganalysis
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In this post we'll talk more on **Steganalysis** - a method of detecting the use and content of a hidden image. This method involves examining a suspected message, in an attempt to detect any possible hiding method or detect any changes that are likely made by someone in the process.

There is much work on this, in order for you to become a master on this. The key point, I'm going with is **the fact** that, unlike encryption techniques which aim at securing communication from unwanted observers, Steganographic technique, **aim at securing messages by embedding data inside images and multimedia objects** in an innocuous-looking cover.

Types
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Here is some of types that are out here

1. **Least significant bit steganalysis**: This method uses least significant bit of each image to encode and decode secret data.

2.  **Frequency Domain Steganalysis:** Stego-key and secret image will be transformed from spatial to spatial frequency. It's easy to encode data inside spatial domain than in frequency domain as there's no human visible.

    This steg type was made known through the book: [An Introduction to Digital Watermarking by M. Arnold, M. Bellamy and K.Miu, IEEE, 1999.][4]
3. **Color Image steg analysis: Color Image is a more common method to use as it allows for a wider scope in embedding more data, since color has three color components, (Red Green, and blue).

Types
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1  * Least Significant bit(LSB):*

Least Significant Bit method (also called Least significant Bit ( LSB) substitution, least Significant bit ( LSB ) is used in Steg methods where we hide our secret data using least Significant Bit of an image and is the easiest steg method as we don't require much complexity for this. 

This is a basic concept used widely. 

This steganographic technique was invented by **Stine** (USA). This method works well in image Steg where each Pixel is used in 8-bit representation in image data where we take last least Significant bit and we hide data with that LSB of each image.

The following diagram is showing that

*   We hide the bits by substituting them to LSB.
    <https\://drive.google\>.com/driv/folder/1KxuQ3jzKjZzj4kQqg6e3y3j5z5Q>

The image we used has the value: 01111001. This binary number can represent the ASCII code 109. We change the last bit from 1 to a zero, to obtain 010111000 and 101 (or 8+0 =8), and change this 101 binary value, that 101 can have value (109-  16)= 093 which will look different than 101 in a digital computer

LSb is widely used method as the least Significant bit has the value from the last digit of a number

1   **Color Steg:*

The main concept here is the fact, Color Image, that it's an **Image of color.**

Here you can hide more information using **3 Color** channels in this color channel of the steg images that's called the Color Steg technique which has 24 bit in a Pixel in RGB Color image.

In this case, you will use color values in an image for your steg data which gives  2-  5  more bytes to encode than an RGB  Image of size 512x512, where a normal RGB image  would only give you a 512\*\*

*   <http\:///en\>.Wikipedia\>/Color Image\>
2   *   Color Space:*

 Color Steganography has different colors to work on that will hide more bytes than color channel of image.

3  *   RGB color:*

   <http\:///en\>/wikipedia/rgb\>(RGB stands for Red Green, and blue color).

**Techniques of Color Image:*

**Frequency domain Steg technique*

1. **DCT (discrete cosine transform):* This transform technique will break your image down from 512\*  into a number of DCT Blocks which will then transform from DDC (spacial Domain image).  It is an image Steganography technique in frequency domain

**Tools and Software's**

We use many different tool's and Software to analyze a Steg file

1  **Jpools steganalyzer :**   is one the top rated steganography tool's which is free software for detecting and removing the Stego information.

   You can find it here, <https://drive\.google\>.com/file/ view/dl/\>\*\_\*\_/fileID>

    Here's an excerpt about this from this page, that the tool is capable of extracting steganography files that were made by some popular Steg softwares:

<https\:///drive\.google\. com/view/d/ 1x2y2z1u2y3i34o2>

Here, the page is showing all Stego tools in order to find which is suitable and useful to our use case:

<https://github\#/steagano\#/files/steg tools.zip\>/download\>\#\</>

You can also check [ this tool on Google Code][5], [ here on Google ] [1]: http://jpoolsteganalyzers.com

*   <https://jsteg.github.io/>  (This one works on a web and desktop)

    There