I recently ran into a problem today when I wanted to transfer a folder from my computer at work to my computer at home. The contents of the folder were of considerable size so emailing them to myself was not an option. I had accidentally left my USB stick at home, so that wasn’t an option either.
Instead, I decided to archive the files and hide them in a JPG. What this meant is I could sync the JPG file to my iPod Touch using its built-in Photos application from my work computer, then sync my iPod Touch to my home computer. There’s a number of applications that will allow you to use the iPod like a USB stick, but this method is completely independent of any 3rd-party applications — at least on the iPod side.
It’s important to note at this point that this process was done using a Window computer. While it may be possible to do this on a Mac, the process described below was done using Windows. A RAR file is similar to a ZIP file, in that it is simply an archive file — a way to group individual files into one larger one. The application I used to do this with was WinRAR. Once I had created my RAR archive, I went to Google Images to grab a JPG of a safe, similar to the one seen here. For simplicity, I renamed these files image.jpg and archive.rar. I put these in a folder on my C drive, named rarjpg.
The next step is where the magic happens. I opened up my command line (accessible in Windows XP or lower by going to Start > Run, typing CMD, then clicking OK). The first command I typed was:
cd c:\rarjpg
This switched the current folder to the folder named rarjpg which I created earlier. The next command I used was the following:
copy /b image.jpg + archive.rar combined.jpg
The copy command in MS-DOS allows a user to copy one or more files to a new location. The plus sign tells the command that you want to combine the contents of each file. The combined.jpg is the file where the result of the copy command will be stored. The parameter /b tells the command that the files being manipulated are binary (non-text). For this to work properly, the JPG file must come first, in other words, archive.rar + image.jpg would not give the desired result.
In simplest terms what this code did was take the ones and zeros from the archive and append them to the ones and zeros of the image to create one long string of ones and zeros. To Windows and most image applications (including iTunes and my iPod Touch), the file looks like a standard JPG but with a bunch of junk content at the end. To WinRAR, it looks like a bunch of junk followed by a standard archive file.
You can use this method to store combine any RAR or ZIP archive with any image. The resulting image will work like (and look like) a normal image. Without knowing otherwise, most people would not even think there was anything unusual contained inside the JPG.
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