Melon Cat'

Author

Ben Webb (bjw45)

Description

There is a newer and an older version of this puzzle. This substitution was made during the puzzlehunt when it was realised the original was too non-obvious, and too difficult to solve. Both versions employ slight variations of the same technique, so are explained in parallel below.

This puzzle is an example of Steganography, the art of hiding messages in places where only the sender and intended recipient will look. However, in this case we can see where the message might be hidden, in the regular graininess of the image. It turns out the message is hidden in one of bits of colour information. We could make an image showing only what one bit of each colour value looks like, if we did this for the bit corresponding to 32, we get:

We can very obviously make out the features of the image in this bit. On the other hand, if we look at the bit corresponding to 16, we get:

This very much does not look like the image, and is the same for each of the RGB bytes of a pixel. (In the old version this bit was also obviously part of the image, but did vary across colour channels. See this image for the equivalent of the above). The way this bit changegs is very quick, suggesting this is not image data at all. If we look carefully we see there are gaps every 8th pixel. This suggests that the image data might be ASCII, with one pixel for each bit. (The old version had 3 bits per pixel, one in the relevant bit of the red, then green, then blue channels.)

If we try decoding it as such, using Big Endian (the old version was Little Endian), we get:

Now this is a story all about how
My life got flipped turned upside down
And I'd like to take a minute just sit right there
I'll tell you how I became the prince of a town called Nyan-Air

In West Philadelphia born and raised
On the playground is where I spent most of my days
Chillin' out maxin' relaxin' all cool
And all shootin' some b-ball outside of the school
When a couple of guys who were up to no good
Started makin' trouble in my neighborhood
I got in one little fight and my mom got scared
And said you're movin' with your auntie and uncle in Nyan-Air

This text is a certain well known theme song, with one word substituted for the solution to the puzzle.

Solution

Nyan-Air

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