Classification[edit | edit source]
EOF[edit | edit source]
Classification method: Inserting
Stego type: Pure
Most primitive method, it's about uploading files after ending file. Worked on any file however information carriers are very easy to detect.
Pictures are simple a book example of steganography so they could not miss them either. For example, we'll use it in a flickr server. Flickr on the 200 MB limit for a single photo and still does not support RAW files. Let's see how to avoid this inconvenience.
You can hide the RAW file inside any single container file "on the lug" by pressing it between or near the end of the original file. For convenience, therefore, they should first create a converted version of the RAW file to the equivalent that supports the service (png, jpg). Later:
cat obraz-dla-flickr.jpg file-raw.dng> result.jpg
in Windows (cmd)
copy / b image-for-flickr.jpg + file-raw.dng result.jpg
In Mac OS
cat image-for-flickr.jpg file-raw.dng >> result.jpg
Our final file has hardly changed, except for the size.
LSB[edit | edit source]
- Classification method: Algorithm
This method is probably the easiest way of hiding information in an image and yet it is
surprisingly effective. It works by using the least significant bits of each pixel in one image to
hide the most significant bits of another. So in a JPEG image for example, the following steps
would need to be taken
1. First load up both the host image and the image you need to hide.
2 Next chose the number of bits you wish to hide the secret image in. The more bits used in the host image, the more it deteriorates. Increasing the number of bits used though obviously has a beneficial reaction on the secret image increasing its clarity.
4. Now you have to create a new image by combining the pixels from both images. If you decide for example, to use 4 bits to hide the secret image, there will be four bits left for the host image. (PGM - one byte per pixel, JPEG - one byte each for red, green, blue and one byte for alpha channel in some image types)
Host Pixel: 10110001
Secret Pixel: 00111111
New Image Pixel: 10110011
5. To get the original image back you just need to know how many bits were used to store the secret image. You then scan through the host image, pick out the least significant bits according the number used and then use them to create a new image with one change - the bits extracted now become the most significant bits.
DCT[edit | edit source]
FFT[edit | edit source]
DSSS[edit | edit source]
KLT[edit | edit source]