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There are also programs known as obfuscators that may operate on source code, object code, or both, for the purpose of deterring reverse engineering.
Code is sometimes obfuscated deliberately for recreational purposes. There are programming contests which reward the most creatively obfuscated code: The International Obfuscated C Code Contest, Obfuscated Perl Contest and Obfuscated PostScript Contest .
There are many varieties of interesting obfuscations ranging from simple keyword substitution, use/non-use of whitespace to create artistic effects, to clever self-generating or heavily compressed programs.
Short obfuscated Perl programs printing "Just another Perl hacker" or something like that are often found in signatures of Perl programmers. See: Just another Perl hacker.
Take this infamous example from 'net lore:
Although pretty unintelligible at first glance, it is a legal C program which when compiled and run will generate the 12 verses of The 12 Days of Christmas. It actually contains all the strings required for the poem in an encoded form inlined in the code. The code then iterates through the 12 days displaying what it needs to.
Another example is a program's source listing that was formatted to resemble an empty tic-tac-toe board. Each pass through the program modified the sourcecode to show a turn in the game, to be executed for the next move.
Yet another example is this short program that generates mazes of arbitrary length:
Note the shape of the corridors in the program. If you are going to attempt to run this program, be aware that modern C compilers need an option like -fwritable-strings to allow overwriting of string literals.
One definition of "code obfuscation" is a set of transformations on a program, that preserve the same black box specification while making the internals difficult to reverse-engineer. There turns out to be many such transformations.
For example, dynamic languages such as Java,
C#, and LispLisp is a family of functional programming languages with a long history. Developed first as an abstract notation for recursive functions, it later became the favored language of artificial intelligence research during the field's heyday in the 1970s and store a program's symbol table within the compiled output. One common obfuscation is to rename every class from something descriptive like "Encryption_Index", to a meaningless sequence such as "rb". The class methods can be renamed to a(), b(), etc.When writing source code, programmers generally create a great deal of structure, according to rules from Structured ProgrammingStructured programming can be seen as a subset or subdiscipline of procedural programming, one of the major programming paradigms. It is most famous for removing or reducing reliance on the GOTO statement (also known as "go to"). Historically, several dif, OOP, and other methodologies. Compilers tend to propagate this structure into compiled code. The job of a good obfuscator is to destroy as much as possible of this structure that lends a program to being human-readable.
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