How it works

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This file sharing technology is based on the steganography, that allows to hide any file in the image without possibility to visually detect any changes. You can read more about steganography on the Wikipedia:

Steganography is the art and science of writing hidden messages in such a way that no-one apart from the sender and intended recipient even realizes there is a hidden message. By contrast, cryptography obscures the meaning of a message, but it does not conceal the fact that there is a message. Today, the term steganography includes the concealment of digital information within computer files. For example, the sender might start with an ordinary-looking image file, then adjust the color of every 100th pixel to correspond to a letter in the alphabet—a change so subtle that someone who isn't actively looking for it is unlikely to notice it.

The larger the cover message is (in data content terms—number of bits) relative to the hidden message, the easier it is to hide the letter.

Stated somewhat more formally, the objective for making steganographic encoding difficult to detect is to ensure that the changes to the carrier (the original signal) due to the injection of the payload (the signal to covertly embed) are visually (and ideally, statistically) negligible; that is to say, the changes are indistinguishable from the noise floor of the carrier.

For this reason, digital pictures (which contain large amounts of data) are used to hide messages on the Internet and on other communication media. For example: a 24-bit bitmap will have 8 bits representing each of the three color values (red, green, and blue) at each pixel. If we consider just the blue there will be 28 different values of blue. The difference between 11111111 and 11111110 in the value for blue intensity is likely to be undetectable by the human eye. Therefore, the least significant bit can be used (more or less undetectably) for something else other than color information. If we do it with the green and the red as well we can get one letter of ASCII text for every three pixels.

Our program uses 3 least significant bits (LSB) for red and blue channels and 2 LSB for the green channel. Using lossless compression (PNG), StegoShare provides about 40% capacity (in the 250Mb images you can hide 100Mb file). Visually images looks that there are no any files embedded, human eye cannot detect the difference. 128-bit encryption makes detecting hidden file more difficult.

The following model can be used for anonymous file sharing.
  1. There are two different websites:
    • Torrent tracker for absolute legal photos.
    • Website (blog, forum) with links to the hidden (censored, illicit) files, embedded in the images and located on the legal photo tracker.
  2. Uploading:
    • Download images on the specified theme (for example birds, old cars, plants, bridges, ships etc) from public photo hosting (we recommend Flickr) or take photos with a digital camera, images must be licensed under Creative Commons or be public domain. If there is possibility to select resolution, download images in the maximal resolution (you can hide more information in them). Set of images for hiding each file must be located in the separate folder. StegoShare supports almost all image types (jpg, gif, png, bmp, tiff etc).
    • You can scale (increase resolution) pictures with the GIMP for not more than 150-200% (depends of the images quality). Total resolution of the image indicates how many bytes it can hide (for example, if image has 1280x1024 resolution, it has 1280*1024 = 1310720 pixels and you can embed in it about 1.3 Mb hidden information).
    • File you want to hide must be less than 2Gb, if it is larger - split file on parts with 7-Zip or WinRAR.
    • Run StegoShare, select cover images folder and file that you want to hide, enter password if you want to protect hidden file (recommended). Press "Hide" button and after some time stego images will placed into the "cover images folder / out" directory. Please note, if you will try to hide different file in the same images, contents of the "out" folder will be deleted, therefore rename "out" folder after embedding first file. If there is not enough free space in the images to hide file, you will get a message with demand to add more cover images.
    • Test extracting hidden file from cover images, if OK rename "out" folder and upload it to the photo tracker (list of public trackers:; do not modify contents of the "out" folder, otherwise it will be impossible to extract hidden file), also add description for your images, like this: "Greatest bridges of the world, high resolution, lossless quality (PNG)". On the private website (not photo tracker; try to search "Rapidshare links" or like this in the Google and you will get a list of link-hostings) post link to the photo set with embedded censored file description, for example: "Artist NoNaMe, album "LaLaLa", 16 songs..., MP3 128kbps, (file hided in images, extract with StegoShare (, password: "123")".
  3. Downloading and seeding:
    • Find censored information you are interested in on the private blogs/forums, follow the link, download torrent with stego images.
    • Run StegoShare, activate "Extract" tab, select folder with images you have just downloaded, add it to the list, enter password if file(s) is password protected. You can simultaneously extract multiple image sets (just add more cover images folders to the list), but remember that they all must have the same password or be unprotected. Select destination folder (default "Desktop") and press "Extract".
    • Continue seeding downloaded files without any fear of legal prosecution, read more at the section Legal help and advices.