Author:

• Name: Glyn Anderson
  Location: ID - Republic of Indonesia (Indonesia)

To build:

    make

To use:

    echo something | ./anderson

Try:

    ./try.sh

Judges’ remarks:

This small program might be a nice addition to a digital personal organizer; just in case you are stranded on a desert island and need to signal your distress to passing ships.

The obfuscation in this program is truly masterful. The program is very cleverly obscured without the use of a single #define! Reformatting this program by hand :-) is the easiest way to understand what is going on.

Note about #defines not being used:

In 2023 due to annoying warnings triggered at different times, sometimes interspersed with the output of the program (this happens in macOS), many entries were changed to use fgets(3) instead. However to make the entries more like the original we redefined gets to use fgets. Unfortunately it’s not possible to do it through -Dfoo compiler options so there is a #define in the code now.

Author’s remarks:

This program is a simple filter that translates ASCII text into semaphore code. It reads from standard input and converts all alphanumeric characters to their corresponding semaphore codes. Consecutive whitespace is translated as a single ‘break’ code. Newlines also cause the next code to be output on a new line. All other characters are ignored. The codes themselves are written to standard output as a depiction of a person holding two flags, using only ASCII characters (semaphore smileys, if you will). For example, given the input “Hello, world!”, the output will be:

                  <>       <>       <>    <>                  <>     <>
      _()       ()/      ()/      ()/     _\)       ()       (/_     _\)
    [] /^      |^^      /^^      /^^    [] ^^      |^^|      ^^ [] [] ^^
      <>[      [][     <>][     <>][       ][      [][]      ][       ][


                  <>    []
      _()_      ()/     |()       ()
    [] ^^ []   /^^       ^^|     |^^|
       ][     <>][       ][]     [][]

The program is obfuscated without the use of the preprocessor or any special compilation parameters. In fact, the program doesn’t even bother using any keywords, save the single char at the beginning. This program was crafted using only operator precedence rules, short-circuit evaluation and recursion. Each function contains a single, non-empty statement. (I did have to add a couple of empty statements to format the code properly.) There is a single string constant which encodes the flag positions and other data needed for drawing the semaphore codes.

The preprocessor will provide no help in de-obfuscating this code, and a C beautifier won’t get you very far either. You just have to crunch through it.

An ANSI C compiler will generate several warnings when it compiles this program, as none of the functions declare their return type, nor do they return anything. This was necessary to keep the program free of keywords. It’s valid in K&R C, and compiles in ANSI C. There are also warnings about conversion from int to char and the resulting loss of data. Again, if it’s OK with K&R, it’s OK with me.

This program is a great teaching tool for learning the semaphore code; and if you don’t have any flags handy you can just use two copies of the source file.

Primary files

• anderson.c - entry source code
• Makefile - entry Makefile
• anderson.orig.c - original source code
• try.sh - script to try entry

Secondary files

• 2000_anderson.tar.bz2 - download entry tarball
• README.md - markdown source for this web page
• .entry.json - entry summary and manifest in JSON
• .gitignore - list of files that should not be committed under git
• .path - directory path from top level directory
• index.html - this web page

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