How is steganography implemented in php

php steganography
Sachindra picture Sachindra · Dec 9, 2009 · Viewed 7.1k times · Source

Somewhere I found out steganography .. the way of storing or hiding information within another information.. at times certain images are also used to hide the information.. Can i get an example or any thing further to know more about how this is implemented... or if at all is it possible to use this in php

Answer

Andrew Keith picture Andrew Keith · Dec 9, 2009

Generally , if your talking about steganography, then basically you are stuffing information into the nooks and crannies of the image file. You can use nearly any image library out there as long as the image library doesn't validate the image file strictly against a schema. You can use nearly any programming language you fancy.

There are numerous techniques. Here are some which are easy to program.

  • Use an image format which stores the image in chunks. You can move the chunks to allow gaps in the file. You can then hide strings of information in the gaps.
  • Convert the image to an indexed image. Declare a pallete larger than the number of colors. Now you can hide extra information in the pallete colors not used in the image.
  • If you are using an image format which has layers, you can declare a layer in which the alpha channel is maximum. This causes the layer to be fully transparent. You can use another color channel to hide your data.

There are numerous more techniques. Remember to use generous amounts of compression and random misleading data to make the image file look legitimate.

Related questions

GD imagejpeg() compression?

I'm working on a project where I edit the pixels of a jpg in PHP using the GD library. Its very crucial and key to my project that the output from PHP retains the pixel values I set (cough-steganography-cough). This …

Read More
How do I check if a string contains a specific word?

Consider: $a = 'How are you?'; if ($a contains 'are') echo 'true'; Suppose I have the code above, what is the correct way to write the statement if ($a contains 'are')?

Read More
Get the full URL in PHP

I use this code to get the full URL: $actual_link = 'http://'.$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF']; The problem is that I use some masks in my .htaccess, so what we see in the URL is not always …

Read More