What the Shed Looks At

Thursday, July 2, 2009


Ok, I promised to do a post on Steganography, or in other words hiding shit in picture files.

Actually this is a really a very simple from of digital steganography. Steganography is simply hiding data in some other data that appears innocuous. This differs from encryption in that there is no knowledge of anything secret by anyone except the message sender and the recipient. Encryption makes a message unreadable, steganography makes it unnoticed.

Very basic steganography can be used to hide compressed archive files inside of picture files and included on webpages, including this blog.

To access these files, you need to save the full picture (not the thumbnail) on to your desktop. Then simply open the file with Winrar. Other Archivers might work, but I haven't tested anything else.
Do this by right clicking the file, select 'open with', select 'choose program', then find 'Winrar Archiver'. The files should be visible if they are there. If not you will get an error.

To make a picture with hidden files you will need to brush up on your DOS:

  1. Place a picture file and a rar archive containing the files you want to hide in the same folder.
  2. Click start, Run..., type cmd, then hit enter.
  3. A command prompt should open (black window with text).
  4. You must navigate to this folder in the command prompt (using the cd command to change directories, teaching DOS is beyond the scope of this post)
  5. Once you are in the folder you will use the copy command to append the two files together. This is a bit old school, and all it really does is stick the two files together end to end, and creates a new file that is a copy of both files together. The command for this is:
    copy /b picture.jpg + files.rar stuffedpicture.jpg

This creates a new picture called stuffedpicture.jpg that begins with picture.jpg and ends with files.rar. It will display like a jpg, but it will contain the archive files if opened in Winrar.

I have been experimenting with uploading pictures to this blog. It doesn't seem to accept 40 mb picture files. I'll try something smaller, maybe 5 mb like an MP3 file.

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