What is Steganography?

What is Steganography?

Steganography is a technique which is used to hide data in an Image file. Data encryption is also used to hide the data in any other form by using some algorithm or substitution text. Unlike Cryptography which encrypts the data in some other text form, Steganography hides the existence of data, which is an advantage over Cryptography. It can not be known that data is hided in the image file or not unless we tell the receiver for whom the data is meant to be.

These are the two images where 1st image is original image which does not contain any text data and 2nd image cantons text hidden inside the bits of original image. Basically we can't see the difference between these two images because only few bits of original image has been tempered and replaced with the text data i stored. Before Steganography the size of the image was 130 KB and after applying 30 KB of text in the image using a Steganography software, the size of the original image has been increased by 30 KB so after steganography image file which has to be sent to someone will be increased to 160 KB.

Sender and receiver both needs a same Steganography software to hide and unhide data. Because algorithm is applied to replace the bits from the Image with the text to be sent. Only same software can fetch the data from the image by which data is hided. There are 100's Steganography Software's available on internet.

We can also develop your own software with very simple C language program in which we can replace every 1000th bit with the text file where text is written, and other program which can fetch and split the data from every 1000th bit of the image file to make it visible for the viewer/receiver.

We can follow any pattern to make steganography software it is not necessary to change 1000th bit of image file. The pattern we will follow to merge the text file with image file, the same pattern we have to follow to extract the text file from image file. So there will be two separate programs to Hide and Extract text from the image.

Why we can see any difference in image file?

Both images seems same but 1st image is original and 2nd is replaced with the text. I took an example of 1000th bit means if we replace every 1000th bit of an image file then the mising pixels were far away from each other so we would not be able to see missing pixels from our eyes easily. But if we replace sequence of 100-200 bytes from one position only then we would be able to see the clarity of image.

If any question or need software to test steganography then leave a comment.