1. Steganography and Network SecurityBy
Sravya Nagaraju

2. Contents: Introduction Frame works Categories Image Steganography
Applications
References

3. INTRODUCTION
Steganography:
Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message.

4. Frame Work:

5. Categories:

6. Image Steganography:
Image Steganography is the technique of hiding the data within the image in such a way that prevents the unintended user from the detection of the hidden messages or data.

7. For Example Original image Stego Image
Image sources:

8. Methods: Image Domain Least significant bit Substitution
Pixel indicator
Stego Color Cycle
Max Bit
Pixel value Differencing

9. Image Domain:
Images are made up of lots of little dots called pixels. Each pixel is represented as 3 bytes – one for Red, one for Green and one for Blue.
Each byte is interpreted as an integer number, which is how much of that color is used to make the final color of the pixel.
= Orange Color

10. The difference between two colors that differ by one bit in either one red, green or blue value is impossible detect for a human eye.
So we can change the least significant (last) bit in a byte, we either add or subtract one or more values from the value it represents.
This means we can overwrite the last bit in a byte without affecting the colors it appears to be.

11. A common approach of hiding data within an image file is Least Significant Bit (LSB) Substitution.
In this method, we can take the binary representation of the hidden data and overwrite the LSB of each byte within the cover image.

12. Least significant bit Substitution:
Suppose we have the following binary representation for the Cover Image.
Suppose we want to "hide" the following 4 bits of data: 1011,
we get the following,
Where the each data bits are accommodated in the least significant bits of each byte of the image.

13. Least Significant Bit Substitution results in a very minor distortion of the image which is very much negligible for the human eyes.
Original Image
Stego Image
Image source:

14. Pixel Indicator:
This method uses the least two significant bits of one of the channels to indicate existence of data in the other two channels.

15. Stego Color Cycle:
The SCC technique uses the RGB images to hide the data in different channels.
It keeps cycling the hidden data between the Red, Green and Blue channels, utilizing one channel at a cycle time.

16. Max Bit:
This method measures the intensity of the pixel and then hides data by random pixel selection with a goal to hide maximum data in each pixel.
This method is divided into three parts:
Encryption
Image Intensity Calculation
Steganography.

17. Original Image Grayscale Image Intense Pixels
All Black colored pixels are considered as Intense pixels
Image source:

18. Pixel Value Differencing:
Pixel Value Differencing (PVD) is able to provide a high quality stego image in spite of the high capacity of the concealed information.
That is, the number of insertion bits is dependent on whether the pixel is an edge area or smooth area.
In edge area the difference between the adjacent pixels is more, whereas in smooth area it is less.
Smooth Area
Edge Area
While human perception is less sensitive to subtle changes in edge areas of a pixel, it is more sensitive to changes in the smooth areas

19. Applications of Image Steganography
Secure Private Files and Documents.
Hide Passwords and Encryption Keys.
Transport Highly Private Documents between International Governments.
Transmit message/data without revealing the existence of available message.

20. References: http://www.garykessler.net/library/steganography.html

21. Questions ?

22. Thank You