A Thought Provoking Question

[Demosthenes]

Here is a little game. This might sound a bit odd given the current state of affairs, but it is only a product of an underworked mind creating its own problems.

The challenge is to send information across open channels and have it picked up by an intended receiver. Encryption would do the job, but would draw unwanted attention and perhaps an inquery into the sender and receiver. So, how to send completely unencrypted information across an unencrypted open channel?

This could work with any file really, I just chose a video since I am biased towards computer animation. Let us assume an AVI since most everyone is familiar and comfortable with them. A relatively short 10-20 second film is created that can be seemlessly repeated. Somehow, we must get the film to repeat itself, without having to make Windows do it (something akin to the "repeat" feature of the hateful Windows Media Player). So, we would need the end of the AVI to point at its beginning somehow. This way, the 10-20 second AVI repeats itself let us say 10 times, creating a 100-200 second (1:40-3:20 minute) AVI with the same size. Now, since this AVI is only 10% of its expected length, we can easily fill the remaining 90% with the unencrypted information, which would need to be hidden from Windows Media Player. In this manner, all would appear well. Most would not even know how to beyond the disguise and those who do know would not give the thing a second glance. Hopefully only those who knew to look would find upon the information.

Programming only taught me nothing is impossible; it is only so difficult that no one tries it. So, any thoughts on its plausibility or other ways to play the game?

Respectfully,

Demosthenes

[Paul Victorey]

This seems similar to the idea of steganography. One flaw I see with your basic approach is that if you are being eavesdropped upon, they will be analyzing the raw byte stream, not looking on a file-by-file basis -- so hiding something by merely putting it in a different file won't help, you actually need to encode the information into the file.

Steganography is like this; you can take an image, and actually insert another file into it, for the most part entirely transparently.

Here's a simple idea:

Take your file that you wish to hide, and add a small header with the file name and length. Take a 24-bit bitmap which has 3 times as many pixels as the "hidden" file has bits.

Now, store each bit of the original file by replaacing the least significant bit of the color component of each color. Because the least significant bit of each component is barely noticable, the image *actually looks the same* afterwards. To remove the file, you look at the first few RGB components of the image, and see if they match a signature you put in the header. If they do, you read the file length from the header, and recreate it.

You could probably do the samw with an AVI, but using all of the keyframes in place of the single image that you would use in a BMP.

[Demosthenes]

No kidding. I knew someone who used to work for a government agency who explained that technique to me a while ago. He always told me that if someone pissed him off he use a similar technique to hide a program that would open a connection to some government computer and simulate an attack long enough for them to trace it. This was before the internet is what it is now and before I knew better, but I always thought he was BS-ing me.
Looks like I might have been wrong about him. Scary thought.

Respectfully,

Demosthenes