OP here. Just to clarify - the contest is ran by the Microsoft student division. Yes, I am aware that it is Facebook only and there is no webpage. I have no control over that, so again - cannot do anything about it. The PDF rules are linked from the same Facebook promotion page, by the way, so if there is any suspicion about that - feel free to read them from the FB page instead of the post.
Windows Phone because I already have experience with .NET, so it was extremely easy to get started. Besides, exciting to be a part of an ecosystem where you can highlight your efforts from the very beginning of its existence.
Interesting project. Might add options not only to corrupt the JPEG file, but also to compress the text inserted and to add the steganography capability, where the text is inserted in the image without corrupting it.