Remove hint.html and index.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta name="GENERATOR" content="mkd2html 2.1.5a DL=DISCOUNT">
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<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8">
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<link rel="stylesheet"
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type="text/css"
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href="../hint.css">
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<title>Best use of cocoa - Bronze award</title>
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</head>
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<body>
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<h1>Best use of cocoa - Bronze award</h1>
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<p>Daniel Vik<br>
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<a href="mailto:daniel@vik.cc">daniel@vik.cc</a><br>
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<a href="http://danielvik.com/">http://danielvik.com/</a></p>
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<h2>Judges' comments:</h2>
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<h3>To build:</h3>
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<pre><code>make vik
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</code></pre>
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<p>This entry requires <a href="http://www.zlib.net/">Zlib</a>.</p>
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<h3>To run:</h3>
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<h4>Embed text (from file or command line):</h4>
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<pre><code>./vik e base.png filename > encodedimg.png
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# or
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./vik e base.png SomeRandomText > encodedimg.png
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</code></pre>
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<h4>Extract the embedded text:</h4>
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<pre><code>./vik d encodedimg.png
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</code></pre>
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<h4>Embed a PNG into another</h4>
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<pre><code>./vik e base.png source.png > encodedimg.png
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</code></pre>
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<h4>Extract the embedded PNG:</h4>
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<pre><code>./vik d encodedimg.png > restored.png
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</code></pre>
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<h3>Try:</h3>
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<pre><code>./vik e ioccc.png chocolate.png > chocolate-in-ioccc.png
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./vik e chocolate.png ioccc.png > ioccc-in-chocolate.png
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./vik d chocolate-in-ioccc.png > restored-chocolate.png
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./vik d ioccc-in-chocolate.png > restored-ioccc.png
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</code></pre>
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<h3>Selected Judges Remarks:</h3>
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<p>References to chocolate had no effect on judging this entry. We
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guarantee it.</p>
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<p>Can you discern hidden pieces of chocolate in chocolate-in-ioccc.png ?</p>
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<h2>Author’s comments:</h2>
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<h2>Introduction</h2>
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<p>This program is a steganography application for embedding an image or text
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into another image as well as extracting the embedded image or text back.
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The program stores the embedded image or text in the low bits of the RGB
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values.</p>
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<p>The program supports any 8 bit true color PNG images (RGB, RGBA, grayscale,
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and grayscale+alpha). The output image is always 8 bit RGB. When embedding
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one image into another, the width and height needs to be the same.</p>
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<p>The program only updates the IDAT and IHDR chunks of the source image. Any
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additional chunks are copied into the resulting image.</p>
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<h3>Bonus Extractor:</h3>
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<p>For some reason the chocolate image seems to have some special properties.
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Apart from being quite big and a little bit noisy, it appears that when
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embedded into another image and extracted, the bitmap data is also a valid
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brain$#@$ program. It is of course possible to get the bitmap data from the
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extracted image, and run it through any of the previous winning brain$#@$
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interpreters, but I thought it would be easier to include an interpreter in
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the program to avoid the hassle:</p>
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<pre><code>./vik e ioccc.png chocolate.png > encodedimg.png
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./vik b encodedimg.png
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</code></pre>
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<p>It is of course also possible to embed a brain$#@$ program as a text file
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(as explained above) and decode it, e.g.:</p>
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<pre><code>./vik e ioccc.png .+[.+] > encodedimg.png
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./vik b encodedimg.png
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</code></pre>
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<h3>Obfuscation</h3>
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<p>I really wanted to keep the program simple, so instead of adding multiple
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macros or helper methods that can be confusing, I placed all functionality
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in the main function. Main is called recursively and quite extensively, but
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it gives the benefit that all invocations of the function has the same
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parameters, argv and argc. This really helps readability, as a programmer
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doesn’t need to remember several variable or function names. I also tried
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to reduce the number of keywords, and the program only has four for-loops
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followed by a single return statement. There is a little bit of use of the
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question mark operator, but this is really there to keep the program as
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simple as possible.</p>
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<h3>Portability</h3>
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<p>The program is portable to most platforms that have zlib available. The
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only system dependency is that the program relies on writing binary data to
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stdout.</p>
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<p>By default, Microsoft compilers adds carriage returns to new lines, and to
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compile the program on this platform, the following line can be added after
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the variable declarations in the main declaration in order to run
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correctly:</p>
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<pre><code>_setmode(_fileno(stdout), 0x8000);
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</code></pre>
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<h3>Limitations</h3>
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<p>The program doesn’t have many error checks so passing in invalid arguments
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or images of mismatching sizes, or unsupported pixel formats will cause the
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program to crash.</p>
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<h3>Extendability</h3>
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<p>Since a lot of care was taken to keep the code simple, it turned out to be
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quite easy to extend functionality. I did include a small brain$#@$ after I
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realized that the chocolate image had some interesting properties.</p>
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<p>But there is more functionality I added that didn’t fit within the size
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limits and could not remain included. For example, I added a method to
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format source code based on a PNG image. So the format of the program is
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actually done by the program itself.</p>
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<p>And to be honest, the chocolate image did not have a brain$#@$ program
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embedded to begin with. I added functionality to the program to embed a
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brain$#@$ into a PNG image and used it to create the image provided with
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the entry.</p>
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<p>I also added a method to analyze PNG images, to print the size and format,
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as well as the scan line filters.</p>
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<p>All these features were quite easy to add, much thanks to the (actually
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pretty good) design of the code.</p>
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<hr />
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<TABLE><TR>
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<TD><a rel="license" href="http://creativecommons.org/licenses/by-sa/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-sa/3.0/88x31.png" /></a></TD>
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<TD><P>© Copyright 1984-2015,
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<A HREF="/judges.html">Leo Broukhis, Simon Cooper, Landon Curt Noll</A>
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- All rights reserved<BR>
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This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-sa/3.0/">Creative Commons Attribution-ShareAlike 3.0 Unported License</a>.</P></TD>
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<TD> <!--<a href="http://validator.w3.org/check?uri=referer"><img src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01 Transitional" height="31" width="88"></a>--></TD>
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</TR></TABLE>
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</body>
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</html>
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